Sudipta Roy

• Definition and Overview of Binary Subtractor
• Half Subtractor
• Full Subtractor
• N -bit Subtractor
• Applications of binary subtractor
• VHDL implementation of half subtractor and full subtractor

Definition

A subtractor is a device that subtracts two numbers and produces the result. A digital or binary subtractor is something that deals with the Subtraction of binary digits.

A binary subtractor is needed for digital computation inside a digital device or a digital computer. The most convenient way of Subtraction unsigned binary numbers is the method of complements. There are rules for binary Subtraction.

The binary subtraction rules are stated as follows. Here 0 is logic low, and one is logic high. A and B are two inputs.

Example of subtraction operations:

1101 – 1011

1101

– 1011

= 0010

So, the answer is 0010

Methods of complements can alternatively carry out binary subtractions for binary subtractors. There are two types of complement methods that are generally used.

A.  1’s Complement

B. 2’s Complement

Steps for performing 1’s complement:

1. Find out the 1’s complement of the number that is to be subtracted.
2. Now the 1’s complement is added to the number from which the Subtraction is desired.
3. Where there is one carry in the last position, of the result of the addition in step 2, the carrier is removed and added to the product without the carry to obtain the final result.

Let us take an example – 1101 – 1011

1’s complement of 1011 = 0100

Now, add 1101 with 0100

1101

 + 0100

 = 1 0001

As we can see, there is one as a carry, so we remove the carry and add the carry again with the obtained result.

0001

+    1

= 0010

So, the answer to the Subtraction is 0010

For 2’s complement method

1. Calculate the 2’s complement.
2. The complement is now added with another number.
3. The carry is rejected.

Let us take an example – 1101 – 1011

2’s complement of any number is calculated by performing 1’s complement and adding 1 to it.

2’s complement of

Now, add 1101 with 0100

1101 + 0100 = 1 0001

As we can see, there is one as a carry, so we remove the carry and add the carry again with the obtained result.

0001 + 1 = 0010

So, the answer to the Subtraction is 0010

Digital computers use the 2’s complement method for calculations as it requires less carry.

The complement methods in the decimal number system are known as 9’s and 10’s complement method.

Various digital circuitries implement this subtraction operation. They are –

• Half Subtractor
• Full Subtractor

A binary subtractor not only performs addition operations but also used in digital applications. Decoding and encoding of values, calculation of the index is a few of its applications.

Half subtractor

A half binary subtractor is a binary subtractor that subtracts one bit of data and produces the result. It has two input sides through which we supply the digital logic values, and it has two outputs through which we receive the impact of the operation. The result can be shown in a single digit. The work shows the number in the Subtraction that has the same significance as the individual digits subtracted. The other output shows the borrow bit.

The half subtractor truth table

The working of the half binary subtractor is shown in the following truth table.

Half Subtractor circuit

From the truth table, we can conclude that the first three rows can represent the result using a single digit. In the second row, the work is described using two numbers as it has borrowed as 1.

Difference = A′B + AB′

Borrow = A′B 

So,

Difference = A XOR B

Borrow = A′ AND B

We need one XOR gate, one NOT gate, and one AND gate to implement the logic. XOR gate, NOT gate, an AND gate can also be made using universal gates like NAND and NOR. So, a half subtractor can be designed using only universal gates.

The following image shows A and B as the input and D as the difference, and C as they borrow.

Full Subtractor

Full Binary Subtractor is another kind of binary Subtractor which provides the result of a binary subtraction operation. When two binary numbers are subtracted, except for the least significant digit, there is a borrow-in as B_i-1 and borrow out as B_i. The full Subtractor is designed to handle a borrow-in for each stage. That is how an entire order overcomes the shortcoming of half Subtractor of running borrow-in.

A full subtractor truth table

Full subtractor circuit

Difference = A′ B′ B_in + A B′ B_in′ + A′ B B_in′ + A B B_in 

Borrow = A′ B_in + A′ B + B B_in 

To implement the expression using logical gates, we need to simplify the word further.

Difference = A′ B′ B_in + A B′ B_in′ + A′ B B_in′ + A B B_in 

 Or, Difference = B_in (A′B′ + AB) + B_in ′ (AB′ + A′B)

 Or, Difference = B_in (A XNOR B) + B_in ′ (A XOR B)

 Or, Difference = B_in (A XOR B) ′ + B_in ′ (A XOR B)

 Or, Difference = B_in XOR (A XOR B)

  Or, Difference = (A XOR B) XOR Bin

Borrow = A′ B′ B_in + A B′ B_in′ + A′ B B_in′ + A B B_in 

 Or, Borrow = A′ B′ B_in +A′ B B_in ′ + A′ B B_in + A′ B B_in + A′ B B_in + A B Bin

 Or, Borrow = A′ B_in (B + B′) + A′B (B_in + B_in ′) + B B_in (A + A′)

 Or, Borrow = A′ B_in + A′B + B B_in

The expression can be written in another way –

Bout = A′ B′ Bin + A′ B Bin′ + A′ B Bin + A B Bin     

    Or, Borrow = Bin (AB + A′ B′) + A′ B (Bin + Bin′)

     Or, Borrow = Bin (A XNOR B) + A′ B

    Or, Borrow = Bin (A XOR B) ′ + A′ B

As the circuit diagram shows, A, B, and B_in. The circuit gives two output as difference output and borrows output. The B_in is set to 1 whenever there is borrow in input A. B_in is then subtracted from A and Y.

The general expression can be written as D = A – B – B_in + 2 B_out.

Full subtractors can also be implemented using half subtractors.

N bit Subtractor

In a single bit binary subtractor, Subtraction of only 1 bit can be performed. If we need to perform Subtraction of n -bit, then a n bit binary subtractor is required. An n-bit subtractor can be implemented similarly using subtractors in a cascaded form.

Applications of Subtractors

• Subtractors are often used with adders. Whenever an adder is needed for a circuit, a subtractor is also required.
• ALU, which is responsible for the calculation, and stays inside a microprocessor, also needs subtractors. CPUs also need subtractors for operation.
• Microcontrollers also use subtractors for performing the digital computation.
• Subtractors are also used in Digital Signal Processing Domain.
• Digital computers use a lot of subtractors.

VHDL Implementation of Half Subtractors & Full Subtractors

Half Subtractor Data flow Modelling

Architecture Dataflow

Full Subtractor Dataflow Modelling

Architecture dataflow

1. Definitions and Overview of adder
2. Types of adder
3. Half adder
4. Full adder
5. BCD adder

Definitions:

An adder is a device which add up two numbers and produce the result. A binary adder is something which deals with addition of binary numbers.

A binary adder is a digital device and needed for digital computations. The operation performed in a binary adder, obeys the rules of binary addition. Here two bits corresponding to 2ⁿ are added and the resultant is then added to the carry from the 2^n-1 digit.

The binary addition rules are stated as follow. Here 0 is logic low and 1 is logic high. A and B are two inputs.

Example of addition operations:

• 11111 + 1011 + 101 + 10 + 1
• 11111+ 1011 = 101010
• 101010 + 101 = 101111
• 110001 + 1 = 110010

So the answer is 110010

Types of Adder

This addition operation is implemented by various digital circuitries. They are –

• Half Adder
• Full Adder
• BCD Adder

A binary adder not only performs addition operations but also used in other digital applications. Decoding of address, calculation of index are few of its applications.

Half Adder

A half adder is a type of binary adder which add one bit of data and produces the result. It has two input side through which we supply the digital logic values and it has two outputs through which we receive the result of the operation. The result can be shown in a single digit. The output shows the digit in the sum that has the same significance as the individual digits added. The other output shows the carry bit.

Half Adder Truth table

The operation of the half adder is shown in the following truth table.

Now from the truth table, we can observe that the first three rows can represent the sum using a single digit. At the last row, the sum is represented using two digits as it has 1 as carry. Here the sum is zero and carry 1 must be taken to the position of next higher significance.

Sum = A′ B + A B′

Carry = AB

So,

Sum = A XOR B

Carry = A AND B

To implement the logic, we need one XOR gate and one AND gate. XOR gate and AND gate can also be made using universal gates like NAND and NOR. So, a half adder can be designed using only universal gates.

The following image shows A and B as the input and S as the sum and C as the carry.

Full Adder

Another type of binary adder is full adder. It also adds binary data and produces the output. Now, when two binary numbers are added, except the least significant digit there is a carry-in as C_i-1 and carry-out as C_i. The full adder is designed to handle a carry-in for each stage. That is how a full order overcomes the shortcoming of half adder of handling carry-in.

Full adder truth table

Full Adder Circuit

S_i = A_i B_i C_i-1 + A_i B_i C_i-1 + A_i B_i C_i-1 + A_i B_i C_i-1 + (A_i B_i + A_i B_i) C_i-1   + (A_i B_i + A_i B_i) C_i-1

And the carry comes as:

C_i = A_i B_i C_i-1 + A_i B_i C_i-1 + A_i B_i C_i-1 + A_i B_i C_i-1 

Or, C_i = (A_i B_i + A_i B_i) C_i-1   + (A_i B_i + A_i B_i) C_i-1

Or, C_i = A_i B_i + (A_i B_i + A_i B_i) C_i-1

Now, consider a half adder has inputs A and B. The output sum is S and carry is C. Now the expression of Si and Ci can be obtained from the expressions of Sum and carry of half adder circuit.

S_i = S C_i-1 + S C_i-1

C_i = C + S C_i-1

Now, to implement a full adder using half adders we need two half adders and one OR gate. Full adder implementations using half adders is represented in the below figure.

As we can see in the figure that the first half adder (marked as-) has the input A_i and B_i. The second half adder (marked as-) has inputs of C _i-1 and output of the first half adder that is S. The output of the second half adder are S_i and S C_i-1.

Now, S C_i-1 represents the carry out. The carry of the first half adder that is C and the carry of the second half adder that is S C_i-1 are fed as input of a OR gate. The output of the OR gate is the final carry out of the full adder circuit.

Parallel Binary Adders

A full adder is needed for the addition of bits in each stage of addition except the addition of least significant digits on the other hand two half adders are needed to complete a full adder. It follows the rule that the addition of two n-bit numbers will require 2 * m -1 number of half adder and m-1 numbers of OR gates. This type of binary adders is known as parallel binary adders. The speed of operation of these types of adders are very fast. That is why they are preferred in modern computational devices.  

Let us add 101 and 111 as an example of parallel binary adder. The figure shown below represents the addition.

The first half adder (marked as-1) adds the extreme right-hand bits 1 and 1 to produce the binary sum 0 and the carry 1 according to the rules of binary addition. The output of the half adder is fed into the input of the first full adder (marked as- 2). The other two inputs of first full adder are the two next bits that is 0 and 1. The outputs of the first full adder are 0 as sum and 1 as carry. They are further fed into input of second full adder. The other two inputs are 1 and 1. The outputs of the second full adder is 1 as sum and 1 as carry. So, the result of the summation is 1100.

Now, a point to be noted that in place of a half adder at the least significant digit position, a full adder can be used with its carry input made 0.

BCD Adder

The term BCD in BCD adder stand for Binary Coded Decimal. BCD is a special type of binary encoding where each digit has certain number of bits for representation. The BCD of first 10 decimal value is shown in the table.

BCD adder has two inputs which varies from 0 to 9. The output varies from 0 to 18 and if the previous carry is considered then the range will be up to 19.

The table for BCD adder is given below.

From the above table, we can observe that from 1 to 9 the binary and the BCD is same. From 10 to 19 decimal numbers, both the binary and codes are different.

The circuit diagram of a BCD adder is shown below.

• In the above diagram there is a four-bit binary adder which has input as addended and augend. It has also input of carry.
• The binary adder gives output of the addition and an carry output.
• Now, using the output and the carry the circuit is further designed to find out the final carry.
• The output is further fed into a 4-bit adder.
• Now, the circuit is designed to make the 1^st and 4^th bit of the addended number as 0 and also the 2^nd and 3^rd bit to make as same as Carry. When the carry is 1, the circuit is designed in such a way that the addended will be 0110. 6 is added with augend to get the BCD.

Example of BCD

0110 + 0101 = 1011

Now this is invalid as BCD. The number is greater than 9. So, we have to add 6 to the result.

The final result will be = 1011 + 0110 =

1011 + 0110 = 10001

So the final answer will be 10001

Know about Subtractors! Click Here!

VHDL implementation of Half adder and Full Adder

HALF-BINARY ADDER DATAFLOW MODELLING

HALF- BINARY ADDER BEHAVIORAL MODELLING:

FULL-ADDER DATAFLOW MODELLING

FULL-ADDER BEHAVIORAL MODELLING

1. A capacitor has a voltage difference of 10 V across the plates. It has stored charges of 1000 micro-coulombs. What is the capacitance value?

1. 100 μF
2. 10 pF
3. 0.01 μF
4. 100 pF

Solution: (1). 100 μF.

Answer Hints: We know that capacitance is given as C = Q / V

Q is the amount of charges stored by the capacitor. V is the voltage in between the plates.

Using the equations, we get – C = (1000 * 10 ^-6) / 10 = 100 μF

Click here for Concept of Capacitor!

2. The plates of parallel plate capacitor is right angle in shape. Two sides of them are 2 cm in size. The distance in between two plate given as: 0.1 cm. What will be the capacitance value if the permittivity of the dielectric is 10^-11 F/m?

1. 1 x 10^-14 F
2. 2 x 10^-12 F
3. 2 x 10^-14 F
4. 1 x 10^-12 F

Solution: (2). 2 x 10^-12 F. Try to solve without using the hints!.

Answer Hints: The formula of capacitance is given as-

C =ε A/ d

Here C is the capacitance, ε Refers to the medium’s permittivity. d is the distance. The side of the triangles is – 2cm or 0.02m.

The surface area= ½ * 0.02 * 0.02 = 2×10^-4

ε = 10^-11 F/m d = 0.001m

So, C = 2 x 10^-12 F

3. Find out the equivalence capacitance.

1. 1/3 pF
2. 1 pF
3. 3 pF
4. 9 pF

Solution: (4). 9pF.

Answer Hints: As we can see that The connection is in parallel..

The equivalent parallel capacitance is stated as C_eq = C₁ + C₂ + C₃ + … + C_N

So, the equivalent capacitance is = 3+3+3 = 9 pF

4. Find out the equivalence capacitance of the circuit.

1. 1/3 pF
2. 1 pF
3. 3 pF
4. 9 pF

Solution: (2). 1 pF.

Answer Hints: As we can see, the capacitors are in series connection.

The equivalent series capacitance is stated as 1 / C_eq = 1 / C₁ + 1 / C₂ + 1 / C₃ + … + 1 / C_N

So, the equivalent capacitance is = 1 / (1 / 3+1 / 3+1 / 3) = 3/3 = 1 pF

5. A capacitor has a capacitance value of 1 micro-farad. What does it imply?

1. It stores one coulomb of charge
2. It holds 6.24 x 10¹² electrons
3. It stores one volt
4. It stores one A of current

Solution: (2). It holds 6.24 x 10¹² electrons.

6. What is the effect on capacitive reactance values if the capacitors are connected in series?

1. An increase in total Xc
2. A decrease in real Xc
3. No change in real Xc
4. Reactance does not depend on connectivity.

Solution: (1). An increase in total Xc

7. How an electrostatic field varies if the charge difference is given?

1. Plate differential
2. Plate Distance
3. Dielectric Quantity
4. Plate Area

Solution: 4). Plate Area

8. How the capacitance of a parallel plate capacitor can be decreased?

1. Increasing the gap between the plates
2. If the charge of the capacitor is increased.
3. Decreasing the gap between the plates
4. If the charge of the capacitor is decreased.

Solution: (1). Increasing the gap between the plates

9. A capacitor and an output resistor are connected in series. The circuit will function like –

1. Bridge Rectifier
2. Band-stop filter
3. Low pass filter
4. High pass filter

Solution: (4). High pass filter.

10. Which type of material is used between the plates of the capacitor?

1. Diodes
2. Materials with high impedance
3. Plate divider material
4. Dielectric Material

Solution: (4). Dielectric material.

11.  Which material has the highest dielectric value in the below options?

1. Mica
2. Air
3. Paper
4. Wood

Solution: (1). Mica

12. What is the phase difference for voltage and current in a capacitor only circuit?

1. The voltage lead by 90 degrees
2. The current lead by 90 degrees
3. The voltage lag by 180 degrees
4. The voltage and current has no phase differences.

Solution: (2). The current lead by 90 degrees.

13. What is the effect on capacitance if the dielectric constant is decreased?

1. It remains the same
2. It increases
3. It decreases
4. The capacitor does not function.

Solution: (3). It decreases

14. Which of the following is true about capacitor?

1. C = Q / V
2. V = Q * C
3. C = R * I
4. Q = I / V

Solution: (1). C = Q / V 

15. What is the S.I. unit of capacitor?

1. Henry
2. Ohm
3. Volt / Amp
4. Farad

Solution: (4) Farad

16. What is the value of the Q factor of a capacitor?

1. Q = 1 / RC
2. Q = 1 / (RC)^1/2
3. Q = 1 / ωCR
4. Correct option is not given

Solution: (3). 1 / ωCR

17. What is the capacitor’s time constant?

1. τ₀ = 1 / C
2. τ₀ = RC
3. τ₀ = 1/RC
4. τ₀ = C

Solution: (2). τ₀ = RC

18. Comment Truth or False based on the sentence given.

Statement: Air can serve as the dielectric for the capacitor.

1. True
2. False

Solution: (1). True

19. What is dissipation factor for a ceramic capacitor?

1. tan δ = ESR * ωC
2. tan δ = ESR * 1 / C
3. tan δ = 1 / (ESR * ωC)
4. tan δ = ESR * C

Solution: (1). tan δ = ESR * ωC

What is dissipation factor? Click to Know!

20. What type of ceramic capacitor provides higher stability?

1. Class 1 type
2. Class 2 type
3. Ceramic Disc Capacitor
4. MLCC

Solution: (1). Class 1 type

21. Which dielectric is used for tantalum metal?

1. Tantalum Aluminium Di-Oxide
2. Tantalum Niobium Phosphide
3. Tantalum pentoxide
4. Tantalum phosphide

Solution: (3). Tantalum pentoxide

22. Which type of capacitor has the highest CV product?

1. Ceramic capacitor
2. Tantalum electrolytic capacitor
3. Coupling capacitor
4. bypass capacitor

Solutions: (2). Tantalum Electrolytic capacitors.

Know everything about Tantalum Electrolytic Capacitors…Click to proceed….

23. What is surge voltage?

1. The minimum voltage received from the load.
2. The maximum voltage received from the load.
3. The maximum peak voltage applied.
4. The minimum peak voltage applied.

Solution: (3). The maximum peak voltage applied.

24. Comment Truth or False based on the sentence given.

Statement: Capacitors are polarized.

1. True
2. False

Solution: (1). True

25. How much energy will be stored in a capacitor if the applied voltage is V?

1. ½ CV²
2. ½ CV
3. CV²
4. 1/4 CV²

Solution: (1). ½ CV²

How energy is being stored in a capacitor? Click for answer!

26. Condenser is currently known as –

1. Filters
2. Rectifiers
3. Capacitors
4. Diodes

Solution: (3). Capacitors

27. How the impedance of a capacitor is represented in Laplace transform?

1. Z(s) = s / C
2. Z(s) = 1 / sC
3. Z(s) = 1 / s²C
4. Z(s) = S² / C

Solution: (2). Z(s) = 1 / sC

28. What will be the effect of increasing the electrode area of a plate capacitor?

1. The capacitance remains the same.
2. The energy stored by the capacitor gets decreased.
3. The capacitance value gets reduced.
4. The energy stored by the capacitor gets increased.

Solution: (4). The energy stored by the capacitor gets increased.

29. Which of the following is the symbol for a bipolar dielectric capacitor?

Solution: (4).

30. Which organization gives the standardization for all electrical components, including capacitors?

1. IEEE(Institute of Electrical and Electronics Engineers)
2. NMEA(National Marine Electronics Association)
3. IEC(International Electrotechnical Commission)
4. Correct option is not given.

Solution: (3).IEC (International Electrochemical Commission).

31. How quality factor is related with Dissipation Factor?

1. Q = 1 / tan δ
2. Q = 1 / tan² δ
3. Q = tan δ
4. Q = 1 / ESR * tan δ

Solution: (1). Q = 1 / tan δ

32. Which type of capacitor provides high volumetric efficiency?

1. Ceramic Capacitors of Class 1
2. Ceramic Capacitors of Class 2
3. Ceramic Capacitors of Class 3
4. Ceramic Capacitors of Class 4

Solution: (2). Ceramic Capacitors of Class 2

33. How does frequency is related to the capacitance of a capacitor?

1. An increase in the frequency will cause a increase in the capacitance.
2. An increase in the frequency will cause a decrease in the capacitance.
3. Increasing the frequency will not affect the capacitance.
4. Decreasing the frequency will decrease the capacitance.

Solution: (2). An increase in the frequency will cause a decrease in the capacitance.

34. What is voltage proof for a ceramic capacitor?

1. The surge voltage
2. The applied voltage
3. The load voltage
4. The rated voltage.

Solution: (4). The rated voltage.

35. When does the resonance occurs in a ceramic capacitor?

1. When the imaginary parts of the capacitor impedance and admittance cancel each other.
2. When the imaginary parts of the capacitor impedance and admittance do not exist.
3. When the imaginary parts of the capacitor impedance have a higher value than admittance.
4. When the imaginary parts of the capacitor impedance have a lower cost than admittance.

Solution: (1) When the imaginary parts of the capacitor impedance and admittance cancel each other.

36. What is the dielectric absorption for a class 1 ceramic capacitor?

1. 1% to 3%
2. 7% to 9%
3. 0.3% to 0.6%
4. 0.1% to 0.3%

Solution: (3). 0.3% to 0.6%

37. A capacitor is rated as 105K 240 V. What is the capacitance of the capacitor?

1. 10 µF
2. 105 µF
3. 240 µF
4. 1 µF

Solution: (4). 1 µF

38. A capacitor is rated as 105M 240 V. What is the capacitor’s tolerance value?

1. ±10%
2. ±20%
3. ±30%
4. ±40%

Solution: (2). ±20%

39. What is MLCC?

1. Multipurpose Liquid Ceramic Capacitors
2. Multipurpose Leakage Ceramic Capacitors
3. Multi-layer Crystalline Capacitors
4. Multi-layer Ceramic Capacitors

Solutions: (4). Multi-layer Ceramic Capacitors

40. Which type of capacitor is used in transistor circuits?

1. Air
2. Bypass
3. Paper
4. Ceramic

Solution: (4). Ceramic

41. Which bridge is used for measuring capacitance?

1. Wheatstone Bridge
2. Schering Bridge
3. Both (A) and (B)
4. Correct option is not given.

Solution: (2). Schering Bridge

42. Which type of capacitor has a short shelf life than others?

1. Electrolytic Capacitor
2. Ceramic Capacitor
3. Both (A) and (B)
4. None of the above

Solution: (1). Electrolytic Capacitor

43. Which type of capacitor is useful in high-frequency circuits?

1. Ceramic capacitors
2. Mica Capacitors
3. Bypass Capacitors
4. Air Capacitors

Solution: (2). Mica capacitors

44. Which type of capacitor is used in R.F. tuning?

1. Ceramic Capacitor
2. Parallel Plate Capacitors
3. Electrolytic capacitors
4. Mica Capacitors

Solution: (3). Electrolytic capacitors

45. Which type of capacitor is used for D.C. voltage?

1. Ceramic Capacitor
2. Parallel Plate Capacitors
3. Electrolytic capacitors
4. Mica Capacitors

Solution: (3). Electrolytic capacitors

46. Where does the electric charge is stored in a capacitor?

1. The Dielectric Material
2. The parallel Plates
3. Correct option is not given.
4. Both (A) and (B)

Solution: (1). The Dielectric Material

47. Comment Truth or False based on the sentence given.

Statement: Both Electric field and magnetic field are associated with capacitors.

1. True
2. False

Solution: (2). False

48. Comment Truth or False based on the sentence given.

Statement: If the voltage across the capacitor is doubled, the energy stored will be doubled.

1. True
2. False

Solution: (1). True

49. What is the value of true power inside a capacitor?

1. More than 0
2. Equals to 0
3. Lies in the range of 0 to 1
4. Correct option is not given

Solution: (2). Equals to 0

50. How many time constants are required to charge a capacitor completely?

1. 5
2. 4
3. 2.5
4. 2

Solution: (1). 5

Points of Discussion

Electrolytic Capacitor

Definition

“An electrolytic capacitor can be defined as the capacitor which metal ended anodes. This anode creates an insulating oxide layer.”

The insulating oxide layer functions as a dielectric layer of the capacitor. The oxide layer is roofed by concrete, liquid, or gel electrolytes. This roofed part serves as the cathode of the electrolytic capacitor.

Electrolytic Capacitor Polarity

Symbol of capacitor

Electrolytic capacitors have specific symbol. The symbol in the circuit, let us understand which type of capacitor is this.

A typical Electrolytic capacitor has a higher capacitance-voltage (CV) product per unit volume in comparison to other types. The feeble dielectric layer as well as the broader anode surface helps to achieve that.

Types of Electrolytic capacitors

They have three kinds –

• Aluminum type Capacitors
• Tantalum type Capacitors
• Niobium type Capacitors

This type of capacitor has a large capacitance, which helps them bypass low-frequency signals and store a large number of energies. They find applications in decoupling and filtering circuits.

These types of capacitors are polarized. The reason behind them is their special structure. They must be operated at higher voltages, and more positive voltages should be on the anode and cathode.

The anode of an industrial usable electrolytic capacitor is marked with a plus sign. An electrolytic capacitor can be destroyed by applying a reverse polarity voltage or using an excessive voltage than the rated working voltage. The destruction is hazardous and can create an explosion to fire.

Bipolar electrolytic capacitors is also one of its kind. It can be formed simply by joining two capacitors by connecting anodes to anode and cathode to cathode.

Know about other types of Capacitors & Workings

Family Tree of Electrolytic Capacitors

Electrolytic capacitors have several varieties. The nature of the positive plate and the type of electrolytic used makes the variation. Each of these three types of capacitors uses concrete and non-solid kinds of electrolytes. The tree is shown below –

Principle of charge

This capacitors stores energy just like regular capacitors. It holds power by parting charge in an electrical field in the insulating oxide layer inside the conductors. An Electrolyte is present here, which acts as the cathode. It also forms another electrode of the capacitor.

Construction

These capacitors practice a chemical property of “Valve metals” to create the capacitor. The practice creates a thin layer of oxide when interchanges with a certain type of electrolyte. There are three solid kinds that are practiced as anode in these capacitors.

1. Aluminium – This type of capacitors uses a high purity imprinted aluminium foil with aluminium oxide as the dielectric material.

2. Tantalum – This type of capacitors use tantalum dust which has lowest level of doping.

[ Read About Tantalum Capacitor. Click Here! ]

3. Niobium – This type of capacitors uses a niobium dust pellet which has lowest level of doping.

The property of the anode materials can be studied below –

Material	Dielectric Material	Structure of oxide	Permittivity	Breakdown Voltage(V/µm)
Aluminum	Aluminum Oxide [Al2O3]	Amorphous	9.6	710
Aluminum	Aluminum Oxide [Al2O3]	Crystalline	11.6-14.2	800-1000
Tantalum	Tantalum pentoxide [Ta2O5]	Amorphous	27	625
Niobium	Niobium pentoxide [Nb205]	Amorphous	41	400

We can see that the permittivity of tantalum oxide is three-time more than Aluminium oxide.

Every anode is imprinted with less smooth cover area and has a larger cover area compared to a smothering one. This is done to increase the capacitance per unit volume of the capacitor.

If a positive valued potential is applied across the capacitor’s anodes, a thick oxide barrier layer will be formed. The thickness of the coating area depends upon the applied voltage over the anodes. This oxide layer which is insulator as well, then functions as a dielectric material. The oxide layer generated by the anode can be destroyed if the applied voltage’s polarity is reversed.

After the dielectric formation, a counter needs to match the rough insulating area on which the oxide formed. As the electrolyte acts as a cathode, it accomplishes the matching process.

Electrolytes are categorized mainly in two sections – ‘Solid’ and ‘Non-Solid.’ Liquid mediums with ion conductivity by moving ions are considered non-solid electrolytes. This type of electrolytes can be easily fit on a rough surface. Solid ones work in the rugged structure by using chemical processes like – polymerization for conducting polymers or pyrolysis for manganese dioxide.

Electrolytic Capacitors Capacitance and volumetric efficiency

The working principle of an electrolytic types capacitor is similar as the working of ‘plate capacitor.’

Capacitance is represented by the following equation.  

C = ε*(A /d)

Here,

C is the capacitance.

A is the area of the plates.

d is the distance between two plates.  

ε is the Permittivity of the medium between two plate.

Increasing the electrode area and the dielectric permittivity will increase the Capacitance.

If we look in detail, an electrolytic types capacitor has a weak dielectric layer, and it stays in the boundary of nanometre per volt. There is another reason behind the higher capacitance. It is the rough surface area.

Electrical characteristics

Series equivalence circuitry

The characteristics of electrolytic capacitors is well defined in ‘International generic description IEC 60384-1’. The capacitors can be represented as a flawless corresponding circuit with series connection of electrical components, including all the ohmic losses, capacitive, inductive parameters of an electrolytic capacitor.

The below circuit represents the series equivalent of Electrolytic Capacitors

C represent the capacitance value of the capacitor; RESR represents the series equivalent resistance. Losses due to heat and ohmic effects are also taken into considerations. LESL is the corresponding inductance in series and considered as the self-inductance of the electrolytic capacitor. Bleak is the leakage resistance.

The Capacitance, Standard Values, and Tolerances Parameter of Electrolytic Capacitor

The construction of anode and cathode primarily decides the characteristics of an electrolytic capacitor. The capacitance value of a capacitor is dependent on some factors like the temperature parameters and the frequency. Electrolytic capacitors of non-solid types have a property of deviation towards temperatures. It shows more deviation than solid types of electrolytes.

The unit of the capacitance is typically in microfarad (µF).

• The needed acceptance value of capacitance is determined by the specified applications.
• Electrolytic capacitors do not require the narrow tolerances.

Ready and Category voltage

Rated voltage of Electrolytic capacitor is defined as the voltage at which the capacitor works with full efficiency. If the capacitor is supplied more than the rated voltage the capacitor gets damaged.

If a capacitor is supplied lower voltage than the rated level, it also effects the capacitor. Applying of lower voltages increase the life of the capacitor. Sometimes it increases reliability for tantalum electrolytic capacitors.

Surge Voltage

Surge voltage is the maximum amount of peak voltage that is supplied to the electrolytic capacitors. It is calculated for the period of the capacitor’s usage in a limited number of cycles.

Transient voltage

Electrolytic capacitors which has Aluminium as material has a tendency to show less sensitivity towards transient voltages.

This condition contents only if the frequency and the energy of the transient is comparatively less.

Reverse voltage

A typical electrolytic capacitor is polarized and, in general, entails the anode electrode voltage to be positive in respect to the cathode voltage.

The reverse voltage is seldom used in fixed AC circuits.

Impedance

A typical capacitor is used as a storage component of electrical energy. Sometimes a capacitor is placed to act as a resistive element in an AC circuit. The major application of an electrolytic capacitor is the decoupling capacitor.

Impedance of a capacitor is given by the AC resistance which is frequency dependent and has phase and magnitude at a specified frequency.

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Points of Discussion

1. Definition & Overview
2. Basic Principle
3. Construction
4. Types
5. Electrical Characteristics
6. Symbol

Definition and Overview

A tantalum capacitor is one kind of electrolytic capacitor, which is a passive electrical device. It uses a capsule of spongy tantalum metal as an anode. An insulating layer of oxide covers the anode. The oxide layer further generates the dielectric. It is surrounded by a solid or non-solid electrolyte, which serves as a cathode.

Tantalum capacitors are characteristics of high capacitance per volume or high volumetric efficiency because of its very reasonable and high permittivity dielectric layer. The increased capacitance value differentiates the tantalum capacitor from other types of electrolytic capacitors. It is also a more expensive capacitor than any different electrolytic kind.

This type of capacitor is polarized inherently. To form a non-polarized or bipolar tantalum capacitor, two polarized capacitors are connected in series. Their anodes are oriented in opposite directions.

Basic Principle

Electrolytic capacitors store electrical energy as a typical capacitor. It holds electrical power by separation charge in an electric field in the dielectric oxide layer between two conductors.

The solid electrolyte is the cathode, forming another electrode of the capacitor. An electrolytic capacitor is different from supercapacitors or electrochemical capacitors, where the electrolyte is generally the ionic conductive connection.

A positive valued voltage is applied at the anode side of the tantalum electrolyte capacitor. The applied voltage causes the generation of a thin oxide layer. This oxide layer functions as the dielectric material of the capacitors.

The characteristics of the oxidised layer can be depicted using the below table.

Anode Material	Dielectric Material	Relative Permittivity	Structure of Oxide	Breakdown Voltage (V/μm)
Tantalum Metal	Tantalum pentoxide [Ta2O5]	27	Amorphous	625
Niobium	Niobium pentoxide [Nb2O5]	41	Amorphous	400

The electrolytic works as a cathode for a tantalum electrolytic capacitor. Several types of electrolytes are used. In general, two types of electrolytes are used – soli and non-solid.

Any liquid medium that has an ionic conductivity medium can be treated as a non-solid electrolyte. Concrete types of electrolytes have electron conductivity, and that is why solid electrolytes are more sensitive to voltage sparks. The oxide layer can be damaged if all of a usdden the polarities of the input voltage is reversed.

The working principle of an electrolytic tantalum capacitor is based on a ‘plate capacitor.’ 

The capacitance can be defined as the below-mentioned formula – 

C = ε * (A /d)

C gives the value of the capacitance; A gives the area of the electrode, d represents the distance between the plates, and ε gives us the value of permittivity.

Capacitance can be increased if the electrode area is increased, and the dielectric permittivity is increased.

If we look in detail, a tantalum electrolytic capacitor has a tinny dielectric layer, and its construction is in the range of nm/volt. Also, the voltage strengths of the formed oxide layer are high enough. Now, this thin dielectric is combined with high voltage oxide dielectric and generates high volumetric capacitance. That is why an electrolytic tantalum capacitor has a higher capacitance than an ordinary capacitor. There are also some influences behind the increase in capacitance. That is the rough surface area due to etched and sintered anodes.

The desired voltage rating of an electrolytic capacitor can be easily produced as the oxide layer is dependent on the applied voltage on the anode. Tantalum Electrolytic capacitors have a high “CV product,” explained as the product of capacitance of the capacitor and voltage divided by the volume.

Know more about different types of capacitors!

Construction

A standard tantalum electrolytic capacitor is a blemish capacitor and made up of tantalum powder and sintered into a capsule, which works as the capacitor’s anode. The oxide layer, which works as a dielectric, is made up of tantalum pentoxide. The cathode of the capacitor is a stable manganese dioxide electrolytic.

Anode

As mentioned previously, a tantalum capacitor usages tantalum powder as an anode. The powder is manufactured from pure tantalum metal. Capacitor times volts is the parameter to measure the figure of merit of the powder. 

The metallic powder is bounded by tantalum wires (riser wire) to form the capsule or ‘pellet.’ The bounding wire works as the tantalum capacitor’s anode connection.

Larger surface areas give higher capacitance value. That is why powders having high CV/g and smaller average particle sizes are used for high capacitance low voltage parts. A specific voltage can be achieved if we can choose the correct type of powder and an almost perfect temperature for sintering.  A suitable sintering temperature can be around – 1200-1800 degrees Celsius.

Dielectric

An electrochemical process named anodization forms the dielectric over the tantalum particles. The primary step to creating this is that the ‘pellet’ is submerged into a very frail solution of an acid and the supplied DC voltage.

Like any other electrolytic capacitor, the thickness of the dielectric layer depends upon the total applied voltage. At the beginning of the process, the power supply is kept in steady current mode until and unless the dielectric thickness is reached. After that, the voltage is held, and the current can decay to get zero value. This process provides an unvarying consistency throughout the device.

The chemical equations are represented below.

2 Ta → 2 Ta ⁵⁺ + 10 e⁻

2 Ta ⁵⁺ + 10 OH⁻ → Ta₂O⁵ + 5 H₂O

Formation of oxides also took place on the surface of the material during the process. The oxide ultimately grows into the material. There is a specific way the oxide grows. Each unit thickness of oxide growth, the two-third share goes inside, whereas one-third share goes outside. The limit of the maximum voltage rating is also due to the limit in the oxide growth.

There is a safety margin in the oxide layer thickness.

Cathode

The process to form the cathode is the pyrolysis of manganese nitrate into the manganese dioxide. After the pellet submersion, that is baked to produce the dioxide cover at around 250 degrees Celsius. The chemical equations are represented below.

Mn (NO₃ )₂ → MnO₂ + 2 NO₂

To build up a thick layer of the coat over both internal and external service areas, the process is repeated repeatedly through fluctuating specific gravities of nitrate solutions.

Types of the Tantalum Capacitors

There are several styles of tantalum capacitors.

Tantalum Chip Capacitors: 80% of tantalum capacitors are of this type. They are categorized for surface mounting.

Tantalum ‘Pearls’ capacitors: They are specially designed for PCB mounting. They are dipped in resin.

Axial leaded tantalum capacitors: Mostly used in military, medical and space applications. It has both tangible and non-solid electrolyte.

Know about Ceramic Capacitors!

Electrical characteristics

Series equivalent circuit

Capacitors are designated as an ideal series equivalent circuit with electrical constituents. But, tantalum capacitors can not be marked as idealistic capacitors.

The circuit below specifies the model.

C is the capacitor’s capacitance; R_ESR is the equivalent series resistance, which takes into account all the ohmic losses. L_ESL is the self-inductance of the capacitor. Bleak is the leakage resistance.

Capacitance, standard values, and tolerances

The construction of electrode determines the electrical characteristics of an electrolytic tantalum capacitor.  The capacitance also depends on the frequency and temperature parameters. The unit of the capacitance of an electrolytic tantalum capacitor depends on microfarad (mu f).

• Particular applications determine the required tolerance of capacitance.
• This does not need narrow tolerances.

Ready and Category voltage

The allowable operating voltage for a tantalum electrolytic capacitor is known as rated voltage or nominal voltage.

Applying higher voltage than the rated one may lead to the destruction of the tantalum electrolytic capacitor. Applying lower voltage has also influenced the capacitor. A lower voltage can extend the lifetime. Sometimes it increases reliability for it.

Surge Voltage

IEC/EN 60384 standardized surge voltage is the maximum amount of peak voltage which is supplied as input to the capacitors. It is measured for the duration of the capacitor’s applications in no of cycles.

Transient voltage

If a transient voltage or a current spike is applied to tantalum electrolytic capacitors, which ha stable manganese dioxide as the electrolytic material, that will lead the capacitor to fail.

Reverse voltage

A typical tantalum electrolytic capacitor is polarized and, in general, have need of the anode must be positive relative to cathode. 

Tantalum capacitors can withstand reverse voltage for a short period. Sometimes the reverse voltage may be used for applications in permanent AC circuits.

Impedance

A standard capacitor is considered as a storage component in electrical energy. Sometimes capacitors are deployed in Alternative Current circuits as resistive elements. An electrolytic capacitor is used as a decoupling capacitor in a course. It blocks the DC component of the signal with the help of the dielectric material.

Leakage Current

The leakage current of tantalum capacitors differentiates these type of capacitors or it can be the identity of these capacitors. The value of leakage current be influenced by on the anode’s applied voltage and temperature.

Symbol of capacitor

Electrolytic capacitors have a particular type of symbol for representing circuits. It is almost similar to the regular capacitor symbol, but a plus sign makes a difference.

A ceramic capacitor is a type of electronic component commonly used in various electrical circuits. It is made of ceramic materials and consists of two conductive plates separated by a dielectric material. The dielectric material in a ceramic capacitor is usually made of ceramic compounds such as titanium dioxide or barium titanate. Ceramic capacitors are known for their small size, high capacitance values, and low cost. They are widely used in electronic devices such as computers, televisions, mobile phones, and automotive systems.

Key Takeaways

Property	Description
Small Size	Ceramic capacitors are compact and take up less space in electronic devices.
High Capacitance	They have high capacitance values, allowing them to store and release electrical energy efficiently.
Low Cost	Ceramic capacitors are cost-effective compared to other types of capacitors.
Wide Application	They are used in a wide range of electronic devices and systems, including computers, televisions, and automotive systems.

Types of Ceramic Capacitors

Class 1 type Ceramic Capacitor

Class 1 type ceramic capacitors are a type of ceramic capacitor that are known for their high stability and low losses. They are made using dielectric materials such as mica or ceramic, which have a low temperature coefficient and low dielectric losses. These capacitors are commonly used in high-frequency applications due to their excellent performance at high frequencies. Class 1 ceramic capacitors have a high capacitance value and are often used in electronic circuits where accuracy and stability are crucial.

Class 2 type Ceramic Capacitor

Class 2 type ceramic capacitors are another type of ceramic capacitor that are widely used in various electronic applications. They are made using multilayer ceramic capacitor (MLCC) technology, which allows for a high capacitance value in a small package size. Class 2 ceramic capacitors have a higher capacitance value compared to Class 1 capacitors, making them suitable for applications that require higher capacitance values. These capacitors are commonly used in power applications, decoupling circuits, and filtering applications.

Multi-layer ceramic capacitor (MLCC)

Multi-layer ceramic capacitors, also known as MLCCs, are a popular type of ceramic capacitor used in a wide range of electronic devices. They are constructed using multiple layers of ceramic material, with alternating layers of ceramic and electrode material. MLCCs offer a high capacitance value in a compact size, making them ideal for space-constrained applications. They are commonly used in various electronic devices, including smartphones, computers, televisions, and automotive electronics.

Ceramic Power Capacitors

Ceramic power capacitors are designed to handle high power and high voltage applications. They are specifically designed to provide high capacitance values and low impedance at high frequencies. These capacitors are commonly used in power electronics, such as power supplies, inverters, and motor drives. Ceramic power capacitors are known for their high energy storage capabilities and low ESR (Equivalent Series Resistance), making them suitable for applications that require high power handling and low losses.

Tubular Ceramic Capacitor

Tubular ceramic capacitors are a type of ceramic capacitor that have a tubular shape. They are commonly used in applications that require high capacitance values and high voltage ratings. Tubular ceramic capacitors are known for their high temperature stability and low leakage current. They are often used in power applications, lighting fixtures, and industrial equipment.

Monolithic Ceramic Capacitor

Monolithic ceramic capacitors are compact, surface mount capacitors that are widely used in various electronic devices. They are constructed using a single ceramic block with embedded electrodes. Monolithic ceramic capacitors offer a high capacitance value in a small package size, making them suitable for miniaturized electronic devices. They are commonly used in consumer electronics, telecommunications equipment, and automotive electronics.

In summary, ceramic capacitors come in various types, each with its own unique characteristics and applications. Class 1 and Class 2 ceramic capacitors are differentiated by their dielectric materials and capacitance values. MLCCs offer high capacitance in a compact size, while ceramic power capacitors are designed for high power applications. Tubular ceramic capacitors are used for high voltage applications, and monolithic ceramic capacitors are compact surface mount capacitors used in miniaturized electronic devices.

Construction and Styles of Ceramic Capacitors

MLCC Construction

Ceramic capacitors are widely used electrical components in various applications due to their high capacitance values and excellent performance at high frequencies. The construction of ceramic capacitors involves the use of dielectric materials, such as ceramic, which determines their capacitance and other electrical properties.

One of the most common types of ceramic capacitors is the multilayer ceramic capacitor (MLCC). MLCCs are constructed by stacking multiple layers of ceramic material, each coated with a conductive material on both sides. These layers are then stacked together, alternating between the positive and negative electrodes, to form a compact and efficient capacitor.

The size of the ceramic chip used in MLCCs can vary, depending on the desired capacitance value and the space available on the circuit board. The miniaturization of MLCCs has been a significant advancement in recent years, allowing for higher capacitance values in smaller packages. This miniaturization is achieved by reducing the size of the ceramic layers and optimizing the internal structure of the capacitor.

MLCCs also feature different termination styles, which are the contact points that connect the capacitor to the circuit board. The most common termination styles include the traditional “end contact” and the newer “side contact” designs. The choice of termination style depends on the specific application and the desired impedance characteristics of the capacitor.

MLCC Miniaturizing

The miniaturization of MLCCs has revolutionized the field of electronic circuits, enabling the development of smaller and more compact devices. This advancement has been made possible by reducing the size of the ceramic layers and optimizing the internal structure of the capacitor.

The miniaturization process involves stacking multiple ceramic layers, each with a thickness of only a few micrometers. This allows for a higher number of layers within the same overall size, resulting in increased capacitance values. Additionally, advancements in manufacturing techniques have enabled the production of MLCCs with smaller electrode sizes, further contributing to their miniaturization.

The miniaturization of MLCCs has also led to improvements in their electrical performance. Smaller capacitor sizes result in lower parasitic inductance and resistance, allowing for better high-frequency performance. This makes MLCCs ideal for applications that require high-frequency filtering or decoupling.

Ceramic Capacitor Construction

Apart from MLCCs, ceramic capacitors are also available in other construction styles. One such style is the ceramic disc capacitor, which consists of a ceramic disc coated with a conductive material on both sides. The leads of the capacitor are attached to the coated surfaces, allowing for easy integration into electronic circuits.

Ceramic capacitors are available in various capacitance values, voltage ratings, and temperature coefficients. These specifications determine their suitability for different applications. For example, capacitors with high capacitance values are suitable for power applications, while those with high voltage ratings are ideal for use in high-voltage circuits.

In terms of construction, ceramic capacitors are known for their reliability and long lifespan. They have a low equivalent series resistance (ESR) and can withstand high temperatures, making them suitable for demanding environments. However, it is important to consider the dielectric breakdown voltage and leakage current when selecting ceramic capacitors for specific applications.

In summary, ceramic capacitors, including MLCCs, are versatile components that find applications in a wide range of electronic circuits. Their construction, capacitance values, and other specifications make them suitable for various high-frequency and power applications. The miniaturization of MLCCs has further expanded their usability, allowing for smaller and more efficient electronic devices.

Electrical Characteristics of Ceramic Capacitors

Ceramic capacitors are widely used electrical components in various applications due to their excellent electrical properties and compact size. They are made using different dielectric materials and come in various types such as multilayer ceramic capacitors (MLCCs), ceramic disc capacitors, and surface mount capacitors. In this section, we will explore the electrical characteristics of ceramic capacitors, including their series equivalent circuit, capacitance, impedance, ESR (Equivalent Series Resistance), and more.

Series Equivalent Circuit

The series equivalent circuit of a ceramic capacitor represents its electrical behavior in a circuit. It consists of the actual capacitance, equivalent series resistance (ESR), and inductance (ESL). The capacitance is the ability of the capacitor to store electrical energy, while the ESR represents the resistance encountered by the capacitor in a circuit. The ESL, on the other hand, represents the inductance associated with the capacitor’s leads and internal construction.

Capacitance, Standard Values, and Tolerances

Capacitance is a crucial parameter of ceramic capacitors, indicating their ability to store electrical charge. The capacitance value is measured in farads (F) and can vary depending on the specific capacitor type and construction. Ceramic capacitors are available in a wide range of capacitance values, from picofarads (pF) to microfarads (μF). They also have standard values and tolerances that determine their accuracy in capacitance. Capacitor manufacturers follow specific codes to indicate the capacitance value and tolerance, such as the ceramic capacitor code.

Impedance

Impedance is a measure of the opposition to the flow of alternating current (AC) in a circuit. In ceramic capacitors, impedance varies with frequency due to the inherent characteristics of the dielectric material used. At low frequencies, the impedance of ceramic capacitors is mainly capacitive, while at high frequencies, it becomes inductive. Understanding the impedance characteristics of ceramic capacitors is crucial for their proper application in electronic circuits.

ESR, Dissipation Factor, Quality Factor

ESR, or Equivalent Series Resistance, is an important parameter that affects the performance of ceramic capacitors. It represents the resistance encountered by the capacitor in a circuit due to various factors such as the internal construction, electrode materials, and dielectric properties. A low ESR is desirable for efficient energy storage and discharge in capacitors. The Dissipation Factor (DF) and Quality Factor (Q) are related to the ESR and represent the energy loss and efficiency of the capacitor, respectively.

Ceramic Capacitor ESR

Ceramic capacitors have a unique ESR characteristic compared to other capacitor types. The ESR of ceramic capacitors is generally low, making them suitable for high-frequency applications. However, it is important to consider the ESR when selecting ceramic capacitors for specific applications, as it can affect their performance and reliability. Factors such as temperature, frequency, and voltage can also influence the ESR of ceramic capacitors.

In summary, the electrical characteristics of ceramic capacitors play a crucial role in their performance and application. Understanding the series equivalent circuit, capacitance values, tolerances, impedance, and ESR is essential for selecting the right ceramic capacitors for different electronic circuits and ensuring their reliable operation.

Understanding Ceramic Capacitors

Ceramic capacitors are essential electrical components used in a wide range of applications. They are commonly found in electronic circuits and are known for their reliability and versatility. In this article, we will explore the working principle of ceramic capacitors, their physical appearance, symbols, polarity, markings, and how to read their values using the ceramic capacitor code.

How Ceramic Capacitor Works

Ceramic capacitors utilize a dielectric material, typically made of ceramic, which separates two conductive plates known as electrodes. When a voltage is applied across the electrodes, an electric field is created within the dielectric material, causing it to store electrical energy. The capacitance value of a ceramic capacitor determines its ability to store this energy.

What Does a Ceramic Capacitor Look Like

Ceramic capacitors come in various shapes and sizes, but they are typically small and cylindrical or rectangular in shape. They are often referred to as multilayer ceramic capacitors (MLCCs) due to their construction, which consists of multiple layers of ceramic and electrodes stacked together. The size of a ceramic capacitor can vary depending on its capacitance and voltage rating.

Ceramic Capacitor Symbol

In circuit diagrams, ceramic capacitors are represented by a symbol that consists of two parallel lines representing the electrodes, with a gap between them indicating the dielectric material. The symbol may also include additional markings to indicate the capacitor’s capacitance value and voltage rating.

Ceramic Capacitor Polarity

Unlike electrolytic capacitors, ceramic capacitors are non-polarized, meaning they do not have a specific positive or negative terminal. This makes them suitable for use in both AC and DC circuits. However, it is important to note that some ceramic capacitors have a polarity marking, indicating the side that should be connected to the lower voltage potential in certain applications.

Ceramic Capacitor Markings

Ceramic capacitors often have markings printed on their surface to indicate important specifications. These markings may include the manufacturer’s logo, capacitance value, voltage rating, and sometimes the temperature coefficient. Understanding these markings is crucial when selecting the right capacitor for a specific application.

How to Read Ceramic Capacitor

Reading the values of ceramic capacitors can be done by decoding the ceramic capacitor code. This code consists of alphanumeric characters that represent the capacitance value, voltage rating, and sometimes the tolerance of the capacitor. By referring to a ceramic capacitor code chart, one can easily determine the specifications of a ceramic capacitor based on its code.

Ceramic Capacitor Code

The ceramic capacitor code is a standardized system used to represent the capacitance value, voltage rating, and tolerance of ceramic capacitors. It typically consists of three digits followed by a letter or two digits. Each digit represents a specific value or multiplier, while the letter or two digits indicate the tolerance. By understanding this code, one can quickly identify the characteristics of a ceramic capacitor.

In conclusion, ceramic capacitors are widely used in various electronic applications due to their reliability, compact size, and versatility. Understanding how they work, their physical appearance, symbols, polarity, markings, and how to read their values using the ceramic capacitor code is essential for selecting the right capacitor for specific circuit requirements.

Ceramic Capacitor vs Electrolytic Capacitor

Comparison of Characteristics

When it comes to choosing the right capacitor for your electronic circuits, two popular options are ceramic capacitors and electrolytic capacitors. Each type has its own unique characteristics and applications. Let’s take a closer look at the differences between these two capacitor types.

Ceramic Capacitors:

• Dielectric Materials: Ceramic capacitors use a ceramic material as the dielectric, which is a non-conductive material that separates the capacitor’s plates.
• Capacitance Value: Ceramic capacitors are available in a wide range of capacitance values, from picofarads (pF) to microfarads (µF).
• Capacitor Construction: They are typically constructed using multilayer ceramic capacitors (MLCCs) or ceramic disc capacitors.
• Capacitor Ratings: Ceramic capacitors have high voltage ratings and are suitable for various applications.
• Capacitor Applications: They are commonly used in high-frequency applications, such as RF circuits, power supply decoupling, and noise filtering.

Electrolytic Capacitors:

• Dielectric Materials: Electrolytic capacitors use an electrolyte as the dielectric, which is a conductive material.
• Capacitance Value: Electrolytic capacitors have higher capacitance values compared to ceramic capacitors, ranging from microfarads (µF) to farads (F).
• Capacitor Construction: They are typically cylindrical in shape and have two electrodes immersed in an electrolyte.
• Capacitor Ratings: Electrolytic capacitors have lower voltage ratings compared to ceramic capacitors.
• Capacitor Applications: They are commonly used in power supply circuits, audio amplifiers, and applications that require high capacitance values.

When to Use Each Type

Now that we have compared the characteristics of ceramic capacitors and electrolytic capacitors, let’s discuss when it is appropriate to use each type.

Ceramic Capacitors:

• High-Frequency Applications: Ceramic capacitors are ideal for high-frequency applications due to their low impedance and high resonance frequency.
• Compact Size: They are available in small sizes, making them suitable for space-constrained electronic devices.
• AC Coupling: Ceramic capacitors are commonly used for AC coupling in audio circuits and signal processing applications.
• Temperature Stability: They have a low temperature coefficient, which means their capacitance value remains relatively stable over a wide temperature range.

Electrolytic Capacitors:

• Power Supply Filtering: Electrolytic capacitors are commonly used for power supply filtering and energy storage in electronic devices.
• High Capacitance Requirements: When a high capacitance value is needed, electrolytic capacitors are the preferred choice.
• Polarity: Electrolytic capacitors have polarity, meaning they must be connected with the correct orientation to avoid damage.
• Low-Frequency Applications: They are suitable for low-frequency applications where size and cost are not major constraints.

In summary, ceramic capacitors are often used in high-frequency applications and where compact size is important, while electrolytic capacitors are commonly used for power supply filtering and applications that require high capacitance values. Understanding the characteristics and applications of each type will help you choose the right capacitor for your specific needs.

Ceramic Capacitor Failure Modes

Ceramic capacitors are widely used in electronic circuits due to their small size, high capacitance values, and excellent stability. However, like any electrical component, ceramic capacitors can experience failure under certain conditions. Understanding the failure modes of ceramic capacitors is crucial for ensuring the reliability and longevity of electronic devices.

Causes of Failure

There are several factors that can contribute to the failure of ceramic capacitors. These include:

1. Dielectric breakdown: Excessive voltage or a voltage spike can cause the dielectric material in the capacitor to break down, leading to a short circuit or open circuit failure.

2. Capacitor aging: Over time, ceramic capacitors can experience a decrease in capacitance value and an increase in equivalent series resistance (ESR), which can affect their performance.

3. Thermal stress: Rapid temperature changes or exposure to high temperatures can cause the ceramic material to expand and contract, leading to mechanical stress and potential failure.

4. Mechanical stress: Excessive mechanical stress, such as vibration or physical impact, can cause cracks or fractures in the ceramic capacitor, compromising its functionality.

How to Test Ceramic Capacitor in Circuit

Testing ceramic capacitors in circuit can help identify any potential issues. Here are a few methods to test ceramic capacitors:

1. Visual inspection: Check for any physical damage, such as cracks or bulges, on the ceramic capacitor. This can indicate a failure.

2. Capacitance measurement: Use a multimeter or a dedicated capacitance meter to measure the capacitance value of the ceramic capacitor. Compare the measured value with the specified value to ensure it falls within an acceptable range.

3. ESR measurement: Measure the equivalent series resistance (ESR) of the ceramic capacitor using an ESR meter. Higher ESR values can indicate a potential failure.

4. Dielectric breakdown test: Apply a high voltage to the ceramic capacitor and monitor for any signs of breakdown, such as excessive current flow or voltage leakage.

Do Ceramic Capacitors Fail?

Yes, ceramic capacitors can fail under certain conditions. The failure rate of ceramic capacitors can vary depending on factors such as operating conditions, quality of manufacturing, and environmental factors. However, with proper design considerations and regular testing, the risk of failure can be minimized.

How Long Do Ceramic Capacitors Last?

The lifetime of ceramic capacitors can vary depending on various factors, including operating conditions, voltage stress, temperature, and quality of manufacturing. Generally, ceramic capacitors have a relatively long lifespan and can last for several years or even decades under normal operating conditions. However, it is important to monitor their performance over time and replace any capacitors that show signs of degradation or failure.

In conclusion, understanding the failure modes of ceramic capacitors and implementing appropriate testing methods can help ensure the reliability and longevity of electronic circuits. Regular inspection, capacitance measurement, ESR measurement, and dielectric breakdown testing are essential for identifying potential issues and preventing failures. By taking these precautions, the lifespan of ceramic capacitors can be maximized, contributing to the overall reliability of electronic devices.

Applications of Ceramic Capacitors

What is Ceramic Capacitor Used For

Ceramic capacitors are widely used in various electronic circuits due to their excellent electrical properties and compact size. They are commonly used for decoupling, bypassing, filtering, and coupling applications. The high dielectric constant of ceramic materials allows for high capacitance values in small packages, making them ideal for space-constrained designs.

In addition to their small size, ceramic capacitors offer low impedance at high frequencies, making them suitable for high-frequency applications. They are commonly used in RF circuits, microwave circuits, and high-speed digital circuits. Their low equivalent series resistance (ESR) and low equivalent series inductance (ESL) make them effective in reducing noise and improving signal integrity.

Where are Ceramic Capacitors Used

Ceramic capacitors find applications in a wide range of electronic devices and systems. Some common areas where ceramic capacitors are used include:

1. Consumer Electronics: Ceramic capacitors are used in smartphones, tablets, laptops, televisions, and other consumer electronic devices. They are used for power supply filtering, decoupling, and noise suppression.

2. Automotive Electronics: Ceramic capacitors are used in automotive electronics for various applications such as engine control units, infotainment systems, and safety systems. They are used for voltage regulation, EMI suppression, and filtering.

3. Industrial Equipment: Ceramic capacitors are used in industrial equipment such as power supplies, motor drives, and control systems. They are used for power factor correction, noise filtering, and voltage regulation.

4. Telecommunications: Ceramic capacitors are used in telecommunications equipment such as routers, switches, and base stations. They are used for signal conditioning, filtering, and impedance matching.

5. Medical Devices: Ceramic capacitors are used in medical devices such as patient monitors, imaging systems, and implantable devices. They are used for power supply filtering, noise suppression, and signal conditioning.

Are Ceramic Capacitors Good for Audio

Ceramic capacitors are commonly used in audio applications, but their suitability depends on the specific requirements of the audio circuit. Ceramic capacitors offer advantages such as small size, low cost, and high capacitance values. However, they also have some limitations.

One limitation of ceramic capacitors is their non-linear behavior at high voltages, which can introduce distortion in audio signals. Additionally, ceramic capacitors may exhibit piezoelectric effects, which can cause microphonic noise in audio circuits. For high-quality audio applications, other capacitor types such as film capacitors or electrolytic capacitors may be preferred.

When to Use Ceramic Capacitor

Ceramic capacitors are suitable for a wide range of applications, but there are certain factors to consider when deciding to use them:

1. Frequency: Ceramic capacitors are well-suited for high-frequency applications due to their low impedance at high frequencies. They are commonly used in RF circuits, microwave circuits, and high-speed digital circuits.

2. Size: Ceramic capacitors are available in small packages, making them ideal for space-constrained designs. They are commonly used in portable electronic devices and miniaturized electronic systems.

3. Temperature: Ceramic capacitors have a wide operating temperature range, making them suitable for both low-temperature and high-temperature environments. They are commonly used in automotive, industrial, and aerospace applications where temperature variations are significant.

4. Cost: Ceramic capacitors are generally more cost-effective compared to other capacitor types such as film capacitors or electrolytic capacitors. They offer a good balance between performance and cost, making them suitable for cost-sensitive applications.

In summary, ceramic capacitors have a wide range of applications in various industries and electronic devices. Their small size, high capacitance values, and low impedance at high frequencies make them a popular choice for many electronic circuits. However, it is important to consider the specific requirements of the application and the limitations of ceramic capacitors before selecting them.

Practical Guide to Ceramic Capacitors

Ceramic capacitors are essential electrical components used in a wide range of applications, from electronic circuits to power systems. In this practical guide, we will explore various aspects of ceramic capacitors, including how to make them, find their value, check their value, measure them with a multimeter, calculate their value, use them effectively, solder them, and understand how they are made.

How to Make Ceramic Capacitor

Making a ceramic capacitor involves the use of dielectric materials, which are insulating materials that can store electrical energy. The most common type of ceramic capacitor is the multilayer ceramic capacitor (MLCC), which consists of multiple layers of ceramic material stacked together. These capacitors are widely used due to their small size, high capacitance, and excellent performance at high frequencies.

How to Find Ceramic Capacitor Value

To find the value of a ceramic capacitor, you can refer to the markings on its surface. Ceramic capacitors are often labeled with a code that indicates their capacitance value. This code typically consists of alphanumeric characters that represent the capacitance value, tolerance, and voltage rating of the capacitor. By decoding the markings, you can determine the capacitance value of the ceramic capacitor.

How to Check Ceramic Capacitor Value

Checking the value of a ceramic capacitor is important to ensure its suitability for a specific application. One way to check the value is by using a capacitance meter or a multimeter with a capacitance measurement function. By connecting the leads of the meter to the capacitor terminals, you can measure its capacitance value. This allows you to verify if the capacitor meets the required specifications for your circuit.

How to Measure Ceramic Capacitor with Multimeter

Measuring a ceramic capacitor with a multimeter is a straightforward process. Set your multimeter to the capacitance measurement mode and ensure that the capacitor is discharged. Connect the multimeter leads to the capacitor terminals and observe the reading on the display. This measurement provides an accurate value of the capacitance, allowing you to assess the performance of the capacitor.

How to Calculate Ceramic Capacitor Value

Calculating the value of a ceramic capacitor is useful when you don’t have access to its markings or if you want to verify the value obtained from other methods. The capacitance of a ceramic capacitor can be calculated using the formula:

C = (k * ε₀ * A) / d

Where:
– C is the capacitance in farads
– k is the dielectric constant of the ceramic material
– ε₀ is the permittivity of free space
– A is the area of the capacitor plates
– d is the distance between the capacitor plates

By plugging in the appropriate values, you can determine the capacitance of the ceramic capacitor.

How to Use Ceramic Capacitor

Ceramic capacitors find applications in various electronic circuits, ranging from decoupling and bypassing to filtering and timing. Their high capacitance and low impedance make them suitable for high-frequency applications. Additionally, ceramic capacitors are used for energy storage, voltage regulation, and noise suppression. Understanding the specific requirements of your circuit will help you select the appropriate ceramic capacitor for optimal performance.

How to Solder Ceramic Capacitor

Soldering ceramic capacitors requires careful handling to prevent damage to the component. Start by cleaning the capacitor terminals and the soldering iron tip. Apply a small amount of solder to the tip to ensure good heat transfer. Place the capacitor on the circuit board, aligning the terminals with the solder pads. Heat the joint with the soldering iron while applying solder to create a secure connection. Avoid excessive heat and prolonged soldering time to prevent thermal stress on the ceramic capacitor.

How Ceramic Capacitors are Made

Ceramic capacitors are manufactured through a precise process that involves the construction of multiple layers of ceramic material. The ceramic layers are coated with a conductive material, typically a metal, to create the capacitor plates. These layers are then stacked together, and the edges are terminated to provide electrical contact. The size and shape of the capacitor can vary depending on its intended application. Capacitor manufacturers employ advanced techniques to ensure high-quality and reliable ceramic capacitors.

By following this practical guide, you can gain a better understanding of ceramic capacitors and their various aspects, from making and finding their value to measuring, calculating, using, soldering, and understanding their manufacturing process. Ceramic capacitors play a crucial role in modern electronic systems, and knowing how to work with them effectively is essential for any electronics enthusiast or professional.

Ceramic Capacitor Kits

Overview of Kits

Ceramic capacitor kits are a convenient and cost-effective solution for engineers and hobbyists who frequently work with electrical components. These kits contain a variety of ceramic capacitors with different capacitance values, voltage ratings, and package sizes. They are designed to provide a comprehensive selection of capacitors for various applications in electronic circuits.

The ceramic capacitors included in these kits are made using different dielectric materials, such as multilayer ceramic capacitors (MLCCs) and ceramic disc capacitors. MLCCs are the most common type of ceramic capacitors and are widely used due to their high capacitance values and small size. Ceramic disc capacitors, on the other hand, are suitable for applications that require high voltage ratings.

The capacitor kits typically come with a range of capacitance values, allowing users to experiment with different values to achieve the desired performance in their circuits. Capacitor values are measured in farads (F) or its subunits, such as microfarads (μF) and picofarads (pF). The kits may also include capacitors with different ratings, such as voltage ratings and temperature coefficients, to cater to a wide range of applications.

To make it easier for users to identify and select the right capacitor for their needs, the kits often provide a code or marking system. This system helps users determine the capacitance, voltage rating, and other specifications of the capacitors. It is important to understand these codes to ensure the correct usage of the capacitors in electronic projects.

How to Choose the Right Kit

When choosing a ceramic capacitor kit, there are several factors to consider to ensure it meets your specific requirements. Here are some key considerations:

1. Application: Determine the specific application for which you need the capacitors. Different applications may require capacitors with specific characteristics, such as high frequency, high voltage, or high temperature capabilities.

2. Capacitor Type: Consider the type of capacitor that best suits your needs. Ceramic capacitors are suitable for a wide range of applications due to their excellent performance in terms of capacitance, frequency response, and stability.

3. Capacitance Value: Identify the required capacitance value for your application. This value determines the amount of charge the capacitor can store and release. It is crucial to choose a kit that offers a range of capacitance values to cover your specific needs.

4. Package Size: Consider the available space in your circuit board or project enclosure. Ceramic capacitors come in various package sizes, such as surface mount capacitors (SMD) and through-hole capacitors. Choose a kit that includes capacitors with package sizes suitable for your project.

5. Voltage Rating: Determine the voltage requirements of your application. Ceramic capacitors have different voltage ratings, and it is important to choose a kit that includes capacitors with ratings that meet or exceed your application’s voltage requirements.

6. Temperature Coefficient: If your application involves temperature variations, consider the temperature coefficient of the capacitors. This coefficient indicates how the capacitance value changes with temperature. Choose a kit that includes capacitors with temperature coefficients suitable for your application.

By considering these factors, you can select a ceramic capacitor kit that provides the necessary components for your specific project or experimentation needs. These kits offer a convenient way to have a diverse range of capacitors readily available, saving you time and effort in sourcing individual components.

Remember to consult the datasheets and specifications provided with the kit to ensure proper usage and compatibility with your electronic circuits.

Conclusion

In conclusion, ceramic capacitors are widely used in various electronic devices due to their numerous advantages. They offer high capacitance values in a compact size, making them ideal for miniaturized circuits. Ceramic capacitors also have excellent stability, low cost, and low equivalent series resistance (ESR). They can operate at high frequencies and withstand high temperatures, making them suitable for a wide range of applications. However, it is important to consider the specific requirements of your circuit and choose the appropriate type of ceramic capacitor, such as multilayer ceramic capacitors (MLCCs) or ceramic disc capacitors. Overall, ceramic capacitors are a reliable and versatile choice for electronic circuitry.

Frequently Asked Questions

Q1: What is a ceramic capacitor and how does it work?

A ceramic capacitor is a type of capacitor that uses ceramic material as the dielectric. It works by storing energy in an electric field between two conductive plates, separated by the ceramic dielectric material. The ceramic material’s properties allow the capacitor to store and release electrical energy.

Q2: How can I identify the value of a ceramic capacitor?

The value of a ceramic capacitor can be identified by the markings on its body. These markings usually represent the capacitance value and the voltage rating. If the markings are unclear, a multimeter can be used to measure the capacitance value.

Q3: What are the different types of ceramic capacitors?

There are several types of ceramic capacitors, including disc, multilayer, and monolithic ceramic capacitors. Disc capacitors are simple and inexpensive, while multilayer and monolithic capacitors offer higher capacitance values and are used in more complex electronic circuits.

Q4: What is the purpose of a ceramic capacitor in a circuit?

In a circuit, a ceramic capacitor is used to store and release electrical energy. It can also be used for filtering, where it passes alternating current (AC) and blocks direct current (DC). Additionally, ceramic capacitors are used for coupling and decoupling applications in electronic circuits.

Q5: How can I check if a ceramic capacitor is functioning correctly?

A ceramic capacitor can be tested using a multimeter. By setting the multimeter to the capacitance setting and connecting the probes to the capacitor’s leads, the displayed value should be close to the capacitor’s rated capacitance. If the value is far off or the multimeter displays an error, the capacitor may be faulty.

Q6: Do ceramic capacitors have polarity?

Unlike some other types of capacitors, most ceramic capacitors do not have polarity. This means they can be installed in either direction in a circuit. However, some special types of ceramic capacitors do have polarity, and these are usually clearly marked.

Q7: What is the role of the dielectric in a ceramic capacitor?

The dielectric in a ceramic capacitor plays a crucial role in storing and releasing electrical energy. The properties of the ceramic dielectric material, such as its permittivity, determine the amount of energy the capacitor can store.

Q8: What are the common applications of ceramic capacitors?

Ceramic capacitors are commonly used in a wide range of electronic devices. They are found in power supply circuits for filtering, in audio and RF circuits for coupling and decoupling, and in timing circuits for oscillators and wave generators.

Q9: How long do ceramic capacitors last?

The lifespan of a ceramic capacitor depends on several factors, including its quality, operating conditions, and the electrical load it experiences. Under normal conditions, a ceramic capacitor can last for many years without failure.

Q10: What causes a ceramic capacitor to fail?

Ceramic capacitors can fail due to a variety of reasons, including excessive voltage (which can cause dielectric breakdown), physical damage, and aging. In some cases, manufacturing defects can also lead to early failure.

Discover the vital role of capacitors in electronic circuits: learn about their varieties, applications, and significance in energy management.

Capacitor – Definitions & Overview

Capacitor is one of the most important passive equipment which is able to store electrical energies. It is a two-terminal device. Capacitance is known as the effect of the capacitor.

Ancient forms of capacitor was innovated in the year 1704s. A European experiment back then discovered that electric charge could be reserved in a water-filled glass. Later in 1745, Ewald Georg from Germany found that series-connected high-voltage electrostatic generators can store the amount. Previously capacitors were known as condensers or condensator. Alessandro Volta coined the term in 1782. The term capacitor came into existence in 1926.

There are lots of types of capacitors. The capacitors have at least two conductors in the form of a metallic flat surface separated by a dielectric materials. The conductor may be an electrolyte, foil, thin film, etc. the non-conductor is the dielectric substance, increasing the capacitor’s charge capacity. Materials like – air, plastic film, paper, mica, ceramics are used as a dielectric for the capacitor.

When an external voltage is applied at the terminals of a capacitor, an electric field is produced across the dielectric material. Thus, a positive charge is collected on one plate, and a negative amount is collected on another scale. Capacitors are used in almost every electrical and electronic circuit. The difference between a resistor and a capacitor is that a resistor dissipates energy, whereas an ideal capacitor does not.

Theory of Operation

As mentioned earlier, a capacitor has two conductors separated by a dielectric medium. A capacitor works on the principle of Coulomb’s Law. Coulomb’s law states that –

Thus, a charge on one conductor will generate the force on the other conductor’s carrier, which further attracts opposite polarity charges and ripples the same type of charges. That is how an opposite polarity charge is induced on the other conductor’s surface.

Both the conductors hold an equal amount of charges, and the dielectric material develops the electric field.

Capacitance and Units of capacitance:

The capacitance of a standard capacitor is defined as the charge’s ratio to the conductor to the conductors’ voltage.

C = Q / V

C is the capacitance, Q is the charge on each conductor’s surface, and V is the voltage between two conductors.

The S.I unit of capacitance is given by – Farad(F).

One Farad capacitance is defined as the amount of capacitance a capacitor can generate if one coulomb of charge is applied to each conductor having one volt of voltage.

In practical devices, Capacitance is given by –

C = dQ / dV

* Most of the capacitors available in the market have capacitance rang in micro-farad.

A capacitor may behave differently at different times if it is placed in an active electrical circuit. Its behavior can be characterized by a long time limit and a short time limit.

Long time equivalence of a capacitor acts like an open circuit configuration (no current passes).

The short time equivalent of capacitors act like a short-circuit configuration.

V (t) = Q (t) / C = (1/C) * [ ∫_t0^t I (τ) dτ ] + V (t₀)

Taking the derivatives, we get –

I (t) = dQ (t) / dt = C * [ dV(t) / dt ]

Symbol of Capacitor

There are different kinds of capacitor available. Different types of symbols are also there to represent them. Some of them are represented below using the diagrams. They are very useful to describe the circuit.

A capacitor in a DC Circuit

Let us discuss a DC circuit where a capacitor and a resistor are kept in series with a constant voltage source – V0.

Let’s assume the capacitor was previously uncharged, and the opened switch is closed at time t0.

From Kirchhoff’s Voltage Law, we can write –

Vo = V_R (t) + V_C (t)

V_R (t) is the voltage across resistor ‘R’ at time instant ‘t,’ and V_C (t) is the measured voltage across the circuit’s capacitor at time instant t.

Vo = i (t) * R + (1/C) * [  ∫_t0 ^t I(τ) dτ ]

Taking derivative on both sides, we get –

RC * [ di (t) / dt] + i(t) = 0

At time t, let say tis zero. The voltage of the resistor is Vo and of the capacitor is zero.

At that time, current would be – Io = Vo / R. Now solving the differential equations –

I (t) = (Vo /R) * e ^{(-t / τ0)}

V (t) = Vo (1 – e ^{(-t / τ0)})

τ₀ = RC.

It refers to as the “Time constant” of the circuitry.

A capacitor in an AC Circuit

In an AC circuit, the capacitor produces impedance, which is the vector sum of resistance and reactance. Capacitor’s impedances and reactance is given by the following expressions.

Reactance = X = – 1 / ωC = – 1 / 2πfC

Impedance = Z = 1/ jωC = – j / ωC = –j / 2πfC

Here ω is the angular frequency; j is the imaginary unit.

The impedance depends inversely on capacitance. Increasing the capacitance and frequency causes a decrease in impedance and vice-versa.

Q factor:

Q Factor or Quality Factor of a capacitor is defined as the ratio of reactance to its resistance. The q factor is a measure of efficiency. The formula can be written as –

Q = X_c / R = 1 / ωCR

ω is the angular frequency, C is the capacitance of the capacitor, Xc is the reactance, and R is the equivalent resistance.

Capacitor in Series

The diagram represents the capacitors in the series connection. It shows that the separation distance is added up instead of the plate area. The series of the capacitance acts as a capacitor less than any of its components.

The equivalent capacitance of the given connection, is –

1/C_eq = ∑ 1 / C_i = 1 / C₁ + 1 / C₂ + … + 1 / C_n

Capacitors in Parallel

The diagram represents the capacitors in parallel connection. An equal amount of voltage is applied to every capacitor. Here the capacitances of the capacitors are added up. The connection of the capacitance acts as an adder.

The equivalent capacitance is –

C_eq = ∑ C_i = C₁ + C₂ + … + C_n

Capacitor Types

There is an enormous number of capacitor types, available in the market based on numerous classification parameters. Type of the dielectric material, the device packaging, and the plates’ structure are some of the determining factors to classify capacitor types.

Dielectric Material

Almost every capacitor types have a dielectric substance. Dielectric substances are placed in between two conductors, the charge capacity can be increased. It is best to have a high permittivity material or high breakdown voltage as a dielectric substance.

There are various dielectric materials available like – paper, plastic, mica, ceramic, glass, air, etc.

Based on dielectric materials, some capacitor types are –

• Electrolytic Capacitor
• Tantalum Capacitor
• Ceramic Capacitor

There are also other types, some capacitor types are –

• Voltage-dependent Capacitor
• Frequency-dependent Capacitor
• Parallel Plate Capacitor
• Decoupling Capacitor

Applications of Capacitors

Capacitors are one of the essential devices which are required for almost every electrical circuit. It has numerous applications in various fields. Some of the most important are – 

Energy Storage

A capacitor has the property of charging and discharging. It can store energy when it is disconnected from the charging source. Using this property, capacitors can be used as a battery or rechargeable battery.

Super-capacitors can accept and deliver charges faster than typical batteries and tolerate a more significant number of charging and discharging cycles than a standard rechargeable battery. But it is more extensive.

The quantity of charge stored in the dielectric layer is equal to or greater than the charge stockpiled in a plate of capacitor.

Pulsed power

Capacitors are used in pulsed power applications. Mainly groups of large, primarily constructed, high voltage, and low inductance capacitors are used here.

Banks of capacitors are also used in power supplies to produce smooth outputs in half-wave or full-wave rectifier. Reservoir capacitors can be used for charging up pump circuits.

Industrial Use

This helps to shunt away and hide fluctuations of current from the primary source to ensure a clean power supply for the control circuits. Audio circuits also use several capacitors.

Signal Coupling and Decoupling

Capacitors pass the AC signal but block the DC signals. That’s why capacitors are used in separating AC circuits. The process is recognized as – AC coupling or ‘capacitive coupling.’

A decoupling capacitor safeguards one area of the circuitry from other. They are used in power supply grounds. These are also known as a Bypass capacitor. Decoupling capacitors has applications in the biasing of transistors.

Memory

Dynamic digital memories for binary computers can be made using capacitors.

50 MCQs with Answer Capacitors. Click Here!

Contents

·       Digital-to-analog Converter (DAC)

·       Working of a digital to analog converter

·       Electrical Symbol of digital-to-analog converter

·       Types of digital-to-analog converter

·       Applications of digital-to-analog converter

·       Advantages and Disadvantages of Digital to Analog Converter (DAC)

Digital to Analog Converter (DAC)

A digital to analog converter is an electronic device that does a conversion operation. As the name suggests, it converts a digital input signal into an analog output signal. Digital signals such as digitized music can be converted into analog sounds using a digital to analog converter. It is one of the types of data converters.

A digital to analog converter is also known as DAC, d to a converter, dac converter, D / A converter, etc. An analog to digital converter (ADC) does the reverse operation.  A DAC is required almost every time in the circuit whenever there is a need for ADC.

Know about Analog to digital converter!

Working of a digital to analog converter

A digital to analog converter is an equipment working for digital to analog conversion. A digital signal is defined as the discrete in time and discrete in the amplitude signal. At the same time, an analog signal is defined as the time-continuous and continuous amplitude signal. A DAC covert a fixed-point binary number (abstract adequate precision number) into a physical measurement.

The transformation has several steps in it. A typical digital to analog converter converts abstract data into conceptual sequences of impulses. Then the series is processed using a reconstruction filter. 

A digital to analog converter works based on the Nyquist-Shannon sampling theorem. It states that – an input signal can be recovered from its sampled output if the sampling rate is twice greater than or equal to the highest frequency component present in the input signal.

There are several parameters to measure the performance of a digital to analog converter. The bandwidth of the output signal, the signal to noise ratio are some of the parameters.

Electrical Symbol of a DAC

The below symbol represents a digital to analog converter.

Types of digital to analog converters

The conversion of digital input bits into analog signals can be achieved through different processes. Let’s discuss some of the types –

A. DAC using the weighted resistors method

Let’s get started with a 4-bit digital number. We will convert it into analog. Let the digital number – B₃B₂B₁B₀

The decimal equivalent will be – N = 2³B₃+2²B₂+2¹B₂+2⁰B₀

Here B₃ is the most significant digit (MSB) whereas, the B₀ is the least significant digit (LSB). The circuit here operates to produce an analog output signal weighted according to the bit positions and add them together.

In the circuit, logic voltages, which represents the binary input, is applied to the corresponding resistors using switches. The resistors of the circuits (except feedback resistor R_f) are connected in a weighted way so that the successive ratio is 2. That is – R₀ / R₁ = R₁ / R₂ = R₂ / R₃ = 2. The resistors are also inversely proportional to their numerical significance of the appropriate binary bit.

When the binary bit is zero (0), the switch is turned ON and connected to the ground. If the binary bit is one (1), the controller is closed and connected to the reference voltage V_R.

The current i which will be supplied to the non-inverting terminal is –

i = V_R * ( B₃ / R₃ + B₂ / R₂ + B₁ / R₁ + B₀ / R₀  )

Substituting the values of R₀, R₁, R₂, R₃ we get –

i = (V_R / R) * (2³B₃+2²B₂+2¹B₂+2⁰B₀ )

Since G is virtual ground, the output voltage v_o =

V_o = -i * R_f = – ( V_R / R ) * R_f * ( 2³B₃+2²B₂+2¹B₂+2⁰B₀ )

Now we can observe that the output voltage is proportionate to the numerical value of the binary digits.

The DAC accuracy depends on the resistor’s ratios and their ability to track each other when the temperature varies.

This type of digital to analog converters has some disadvantages. It requires a wide range of resistors to construct the converter if the binary input consists of a large number of bits. The R-2R ladder type converter overcomes this disadvantage.

B. R – 2R Ladder Type DAC

A ladder of resistances can convert a binary word into analog. This type of DACs is known as R – 2R Ladder-type converters.

To understand the circuit’s operation, let us assume that the terminal B0 is connected to VR, and the rest of the terminals (B1, B2, B3) are connected to the ground.  The resulting figure is shown in the circuit –

We apply Thevenin’s theorem to the nodes a0, a1, a2, a3 concerning ground. We get the Thevenin’s equivalent circuit, which is further shown in the below course –

The equivalent source has a voltage of VR/16 in series with a resistance 3R.

Again, if the terminal B1 is connected to Vr and the terminals B0, B2, B3 are connected to the ground, then applying Thevenin’s theorem also, it can be shown that the source has a voltage VR /8 in series with a resistance 3R.

Similarly, when B2 is connected with VR and rest inputs are connected to the ground, we will find that the Thevenin’s equivalent circuit has a source voltage of VR / 4 in series with a resistance 3R.

Same for B3’s connection with VR. The equivalent circuit gives the source voltage as VR / 2 and the series resistance of 3R.

The current i obtained by the principle of superposition – 

i = ( Vr / 3R ) * ( B0/16 + B1/8 + B2/4 + B3/2 )

Since G is virtual ground, the output voltage v_o =

V_o = -i * R_f = – ( V_R / R ) * R_f * (B0 / 23 + B1 / 22 + B2 / 21 + B3 / 20 )

The equation comes as –

V_o = -i * R_f = – ( V_R / 48R ) * R_f * ( 2³B₃+2²B₂+2¹B₂+2⁰B₀ )

Here and now we can realize that the output voltage is proportionate to the numerical value of the binary digits. This circuit can easily convert large binary digits as it is easily extensible. All we need to add is additional switches and extra resistors for the ladder.

One of the vital features of a digital to analog converter is that the circuit’s smallest change defines its resolution.

Applications of digital to analog converter

The modern era has a high demand for digitized data. That is why there is an increasing demand for an analog to digital converter. But we have to keep in mind that we use analog signals in our day-to-day life, and the world is analog. So, whenever we need an analog to digital converter, we need a digital to analog converter. Both DACs and ADCs have contributed most to the digital revolution.

Let us take a real-world example to understand their need. Consider a telephone call. At first, the caller starts speaking. The speech is an analog signal, which is changed into a digital signal using an analog to digital converter or ADC. When the digitized signal is transported to the receiver’s end, it again needs to be converted into an analog signal; otherwise, the receiver will not understand the sent data. Here a digital to analog converter serves the purpose.

Audio Processing:

Music and other audios are stored in digitized format in today’s era of digitalization. When we need to hear them in speakers or headphones, then the digitized form must be converted into an analog signal. That is why DACs are found in every device which can play music like – MP3 Music player, DVD player, CD player, Laptops, Mobile Phones, etc.

High-end hi-fi systems use specialized standalone DACs. Similar DACs are found in modern digital speakers such as USB speakers, sound cards, etc.

In voice over IP communications, the source is digitized. Thus a DAC is needed to reconstruct the digitized part into an analog signal.

Video Encoding:

The video encoder system processes a video signal and sends digital signals to ICs.

Digital Display:

The graphic controller typically uses a lookup table to generate signals sent to analog outputs such as RGB signals to drive the display.

Calibration:

A digital to analog converter can provide calibration of dynamic types to increase the test system’s accuracy.

Controlling Motor:

Digital to analog converters are also used in motor control devices where the voltage control signal is required.

DACs are also used in data distribution systems, digital potentiometer, software radio, and many other places.

Advantages and Disadvantages of Digital to Analog Converter (DAC)

Advantages of DAC

As mentioned earlier a digital to analog converter is as important as an Analofg to digital converter, it has too several points to discuss. Every electrical and electronic device has both its advantages and disadvantages. DACs are no exception. Some of its benefits are –

• Large digital – binary inputs can be converted into its analog form easily.
• One of the fastest methods of conversion.
• Simple circuitries to implement.

Disadvantages of DAC

• Circuits use expensive operational amplifiers.
• Some errors like – gain error, offset error, Non-linearity is generally caused by resister employed in the circuit.
• Power dissipation is high.

Content

·       Analog to digital converter (ADC)

·       Working Principle of an analog to digital converter

·       Electrical Symbol of analog to digital converter

·       Types of analog-to-digital converter & Explanations

·       Applications of analog to digital converter

·       Testing of an analog-to-digital converter

·       An ADC IC

Definition & Overview of Analog-to-digital Converter

An analog to digital converter is an electronic device. As the name predicts, the supplied analog signal is converted into a digital signal which is produced at output. Analog signals such as voice recorded by a microphone can be converted into a digital signal using an analog-to-digital converter. 

An analog to digital converter is also known as ADC and A to D converter, etc.

Working of an Analog to digital converter

An analog signal is defined as the time-continuous and continuous-amplitude signal. At the same time, a digital signal is defined as the discrete-time and discrete-amplitude signal. An analog signal is converted into a digital signal with the help of an analog-to-digital converter. The transformation has several steps, like sampling, quantization, and others. The process is not continuous; instead, it is periodic and limits the input signal’s allowable bandwidth.

An analog-to-digital converter works based on the Nyquist-Shannon Sampling Theorem. It states that – an input signal can be recovered from its sampled output if the sampling rate is twice greater than or equal to the highest frequency component present in the input signal.

There are several parameters to measure the performance of an analog to digital converter. The bandwidth of the output signal, the signal to noise ratio are some of the parameters.

Electrical Symbol of an ADC

The below symbol represents an Analog to digital converter (ADC).

Types of Analog to digital converters

The conversion of input analog signals into digital signals can be achieved through different processes. Let’s discuss some of the types in detail –

A. Flash ADC

Flash ADC is known as direct-conversion type’s analog to digital converter. It is one of the fastest types of analog-to-digital converters. It comprises a series of comparators with the inverting terminals connected to a voltage divider ladder and the non-inverting terminals connected to the analog input signal.

As the circuit shows, a ladder of well-matched resistors is connected with a reference or threshold voltage. A comparator is used at each tap of the resistors’ ladder. Then there is an amplification stage, and after that, the code is generated as binary values (0 and 1). An amplifier is also used. The amplifier amplifies the voltage difference from the comparators and also suppresses the comparator offset.

If the measured voltage is above the threshold voltage, then the binary output will be one, and if the measured voltage is less than the binary work will be 0.

Recently improved ADCs are modified with digital error corrections systems, offset calibrations, and also, they are a smaller size. ADCs are now available in integrated circuits (ICs).

This type of analog-to-digital converters has a high sampling rate. Thus, it has applications in high-frequency devices. Detection using radars, wide-band radios, various testing equipment are some of them. NAND Flash memory also uses flash type analog-to-digital converters to store up to 3 bits in a cell.

Flash type ADCs are fastest in operation speed, simple in circuitries, and conversion coincides instead of sequentially. Though, these requires considerable numbers of comparisons than different types of ADCs.

B. Successive Approximation type ADC

Successive approximation type ADC is another type of analog-to-digital converter which uses binary search through quantization levels before conversion into the digital domain.

The whole process is divided into different sub-processes. There is an ample and hold circuit, which takes the analog input, Vin. Then there is a comparator that compares the input analog voltage with the internal digital-to-analog converter. There is also a successive-approximation register (SAR), which takes input as clock pulse and comparator data.

The SAR is primarily initialized to make the MSB (most significant bit) as logic high or 1. This code is supplied to the digital-to-analog converter, which further provides the analog equivalent to the comparator circuit compared to the sampled analog input signal. If the voltage is more than the input voltage, then the comparator resets the bit. Else the bit is left as it is. After that, the next bit is set to a digital one, and the whole process is again done until every bit of the successive-approximation register is tested. The final output is the digital version of the analog input signal.

There are two types of successive-approximation types analog-to-digital converters available. They are – Counter type and Servo tracking type.

These types of ADCs give the most accurate results than other types of ADC.

C. Integrating type ADC

As the name implies, this type of ADCs converts continuous-time and continuous amplitude input analog signal into a digital signal using an integrator (an integrator) to apply an operational amplifier that takes a usual input signal and gives time-integrated output signal).

An unidentified analog input voltage is applied at the input terminal and allowed to ramp for a certain period, known as the run-up period. A pre-determined reference voltage of opposite polarity is then applied to the integrator circuit. That is also allowed to ramp until and unless the integrator gives the output as zero. This time is known as the run-down period.

The run-down time is generally measured in units of the ADC’s clock. So, longer integration time results in higher resolution. The speed of this type of converter can be improved by compromising with the solution.

As the speed and resolution are inversely proportional, this type of converters does not find digital signal processing or audio processing applications. Preferably, they are used in digital measurement meters (ammeters, voltmeters, etc.) and other instruments where high accuracy is crucial.

This type of ADCs has two kinds – charge balancing analog to digital converter and Dual-slope ADC.

D. Wilkinson ADC

– D. H. Wilkinson first designed this type of analog-to-digital converter in the year 1950.

At first, capacitor gets charged. A comparator checks this condition. After getting to that specified level, now the capacitor starts discharging linearly, producing a ramp signal. A gate pulse is also initiated in the meantime.  The gate pulse remains on for the rest of the time while the capacitor discharges. This gate pulse further operates a linear gate which further receives input from an oscillator clock of high-frequency. Now, when the gate pulse is ON, several clock pulses are being counted by the address register.

E. Time Stretch Analog to Digital Converter (TS – ADC):

This type of Analog-to-digital converter are functioned on a combined technology of electronics and other techs.

It can digitalize a very high bandwidth signal that cannot be done using an ordinary ADC. This is often termed as “Photonic Time Stretch Digitizer”.

It not only analog to digital but also used for high-throughput real-time equipment such as imaging and spectroscopy.

There are several other types of other analog-to-digital converters.

• The Delta-encoded ADC
• The Pipelined ADC,
• The Sigma-delta ADC,
• The Time-interleaved ADCs etc.

What is DAC? Know more about Digital to analog converter! Click to know!

Applications of ADC

The analog to digital converter is one of the most important electronic devices in this modern era. This is an era of digitalization, but our world is analog in real-time. Converting analog data in the digital domain is the need of this hour. That is why they are so important. Some of the significant applications of an ADC are – 

A. Digital signal processing

– Analog to digital converters are essential for editing, modifying, processing, storing, and transporting data from the analog field to the digital area. Microcontrollers, digital oscilloscopes, and critical software find applications in this domain. Devices like digital oscilloscopes can store waveforms for later use, whereas an analog oscilloscope cannot.

B. Microcontrollers

– Microcontrollers makes a device smart. At present, almost all microcontrollers have analog to digital converters inside them. The most common example may be the Arduino. (It is built on an ATMega328p microcontroller) The Arduino provides a useful function of ‘analogRead(),’ which takes analog input signals and returns digital data generated by the ADC.

C. Scientific Instruments

– ADCs are useful for making various necessary electronics instruments and systems. Digital imaging for the digitization of pixels, radar technologies, and many remote sensing systems is an example. Devices like sensors produce an analog signal for measuring temperature, light intensity, light sensitivity, air humidity, air pressure, pH of a solution, etc. All these analog inputs are converted by ADC to generate a proportionate digital output.

D. Audio Processing:

-ADC has a vital application in the field of audio processing. The digitization of music enhances music quality. Analog voices are recorded via microphones. Then they are stored in digital platforms using an ADC. Many tunes recording studios record in PCM or DSD formats and then down sampled for digital audio productions. They are used for broadcast on televisions and radios.

Testing of an analog to digital converter

To test an analog-to-digital converter, first of all, we need an analog input voltage source and electronics equipment to send and control signals and receive the digital output data. Some of the ADCs also requires a source of reference signals. There are some parameters to test an ADC.

Some of them are –

• Signal to noise ratio (SNR),
• Total harmonic distortion (THD),
• Integral nonlinearity (INL),
• DC offset error,
• DC gain error,
• Power Dissipation, etc.

ADC IC

ADCs are commercially available as ICs in the market. Some of the commonly used ADC ICs are ADC0808, ADC0804, MPC3008, etc. They find applications in devices like Rasberry pi and other processors or digital electronics circuits where an ADC is needed.

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List of Topics

• Rectification & Rectifier
• Types of Rectifier
• Bridge Rectifier
• Bridge Rectifier Circuit and Diagram
• Working of a bridge rectifier
• Differences between Bridge Rectifier and Full Wave Rectifier
• Mathematical problems

Rectification

Rectification: The process through which AC voltage is converted into Dc voltage is known as the rectification. Rectifier is the electronics device to perform the rectification

Types of Rectifiers

Rectifiers are mainly three types. They are –

1. Half-Wave Rectifiers (HWR)
2. Full-Wave Rectifiers (FWR)
3. Bridge Rectifier (BR)

Bridge Rectifiers

Bridge rectifiers are kind of rectifiers that converts ac to dc that is alternating current to direct current. This type of rectifier allows both halves of the ac input voltage to pass through the circuit. Four diodes are necessary to make a bridge rectifier.

Bridge Rectifiers Working & Circuit

A bridge rectifier is shown in the below circuit.

Full-wave rectification can also be implemented with the help of a rectifiers, which includes four diodes. As shown in the circuit, two diodes of the opposite arms conduct current simultaneously while the other two diodes remained in OFF state. For Now, the current flows through the diode D1 and D3 but no current flows through the D2 and D4 diodes. This happens because of the instantaneous polarity of the secondary windings of the transformer.  A current I thus pass through the load resistance RL in the shown direction.

Now, the next half of the cycle comes. This time the transformer’s polarity changes. Current flows through the Diode D2 and diode D4 and no current flows through the diodes D1 and D3. The direction of flow of current remains the same as the previous half of the cycle.

Know about How a Transformer works!

Bridge Rectifier Formula and Equations

From the standard Bridge rectifier circuit,

Vi is the input voltage; Vb is the diode voltage, rd is the dynamic resistance, R is the load resistance, Vo is the output voltage.

Average O/p voltage:

V_o = V_mSinωt; 0 ≤ ωt ≤ π

V_av = 1/π * ∫₀^2πVo d(ωt)

Or, V_av = 1/π * ∫₀^2πV_mSinωt d(ωt)

Or, V_av = (V_m/π) [- Cosωt]₀^π

Or, V_av = (V_m / π) * [-(-1) – (-(1))]

Or, V_av = (V_m/ π) * 2

Or, V_av = 2V_m / π = 0.64 V_m

The average load current (I_av) = 2* I_m/π

The RMS (Root Means Square) Value of current:

I_rms = [1/π * ∫ ₀ ^2π I²  d(ωt)]^1/2

I = I_mSinωt; 0 ≤ ωt ≤ π

Or, I_rms = [1/π * ∫ ₀ ^2π I_m²  Sin²ωt d(ωt)]^1/2

Or, I_rms = [I_m²/π *∫ ₀ ^2π Sin²ωt d(ωt)]^1/2

Now, Sin²ωt = ½ (1 – Cos2ωt)

Or, I_rms = [I_m²/π *∫ ₀ ^2π (1 – Cos2ωt)d(ωt)]^1/2

Or, I_rms = [I_m²/2] ^½   Or, I_rms = I_m/√2

The RMS voltage = V_rms = V_m/√2.

The significance of the RMS value is that it is equivalent to DC Value.

Provided that RMS value is ≤ Peak Value

Peak Inverse Voltage (PIV):

Peak inverse voltage or PIV is referred to as the maximum permissible voltage that can be applied to a diode before its breakdown.

Peak inverse voltage of a bridge rectifier is calculated as PIV >= V_m

Applying greater voltage than the peak inverse voltage will damage the diode and effect other circuit elements if associated.

Bridge Rectifier graph

The following graph shows the input output signal of a bridge rectifier. It is same as Bridge Rectifier.

Form Factor

The form factor of a bridge rectifier is the same as a full-wave rectifier and is defined as the ratio of RMS (Root Means Square) Value of load voltage to the average value load Voltage.

Form Factor = V_rms / V_av

V_rms = V_m/2

V_av = V_m / π

Form Factor = (V_m/√2) / (2*V_m/ π) = π/2√2=1.11

So, we can write, V_rms = 1.11 * _Vav.

Ripple Factor

Ripple factor of a bridge rectifier is the percentage of Alternating Current component present in the output of the bridge rectifier.

The ‘γ’ represents the ripple factor.

I_o = I_ac + I_dc

Or, I_ac = I_o – I_dc

Or, I_ac = [1/(2π) * ∫₀^2π(I-Idc)²d(ωt)]^1/2

Or, I_ac = [I_rms² + I_dc²– 2 I_dc²]1/2

Or, I_ac = [I_rms² – I_dc²]1/2

So, Ripple factor,

γ = I_rms² – I_dc² / I_dc²

or, γ = [(I_rms² – I_dc²) – 1] ^1/2

γ_FWR = 0.482

Transformer Utilization Factor

The ratio of DC power to the rated AC power is known as the Transformer utilization factor or TUF.

TUF = P_dc/ P_ac(rated)

V_s / √2 is the voltage rated for the secondary winding and I_m/2 is the current flowing through the winding.

So, TUF = I_dc² R_L / (V_s/ √2) * (I_m / √2)

TUF = (2I_m/ π)²R_L / ( I_m² (R_f +R_L)/(2√2) = 2√2/ π ² * (1 / (1 + R_f/R_L))

If R_f << R_L, then,

TUF = 8 / π ² = 0.812

The more the TUF, the better the performance.

Bridge Rectifier Efficiency

Efficiency of bridge rectifier is defined as the ratio of the DC power supplied at the load to the input AC power. It is represented by the symbol – η

η = P_load / P_in *100

or, η = I_dc² * R/ I_rms² * R , as P = VI, & V= IR

Now, I_rms = I_m/√2 and I_dc = 2*I_m/π

So, η = (4I_m²/ π²) / (I_m²/2)

η = 8 / π² * 100% = 81.2%

Efficiency of an ideal Bridge Rectifier Circuit is = 81.2%

Specify Difference Between Bridge and Full Wave Rectifier

Subject of Comparison	Bridge Rectifier	Full Wave Rectifier
No. of diodes used	Four diodes are used	Two diodes are used
Current flow	Current flows in the circuit for only the positive half of the input cycle.	Current flows in the circuit for all half of the input cycle.
Transformer Required	Any small step-down or step-up transformer	Centre Tapped transformers are the centre required for full-wave rectifiers. It also needs a more oversized transformer than a bridge rectifier.
Peak Inverse Voltage	For a bridge rectifier, peak inverse voltage is the maximum voltage across the transformer’s secondary winding.	For the full-wave rectifier, each diode’s peak inverse voltage is twice the maximum voltage between the center tap and any other end of the transformer’s secondary winding.
Availability	A bridge wave rectifier is available in the market in one package.	Ready-made full-wave rectifiers are not available in the market.
Cost	Cheaper than full-wave rectifiers.	Costlier than bridge rectifier.
Transformer Utilization Factors	Transformer Utilization Factor is 0.812	For a full-wave transformer, TUF is = 0.693
Efficiency for low voltages	Current flows through two diodes in series in a bridge rectifier, and immense power dissipates in the diodes. Hence efficiency is lower in low voltage conditions.	There is no such effect on full-wave rectifiers. Efficiency is more in such a condition than a bridge rectifier.

Some Problems with Bridge Rectifiers

1. A bridge rectifier has a load of 1 kilo- ohm. The applied AC voltage is 220 V (RMS value). If the diodes’ internal resistances are neglected, what will be ripple voltage across the load resistance?

a. 0.542 V

b. 0.585 V

c. 0.919 V

d. 0.945 V

The ripple voltage is = γ * Vdc / 100

Vdc = 0.636 * Vrms * √2 = 0.636*220*√2 = 198 V.

The ripple factor of an ideal full-wave rectifier is 0.482

Hence the ripple voltage = 0.482*198/100 = 0.945 V

2. If the peak voltage of a bridge rectifier circuit is 10 V and the diode is silicon diode, what will be the peak inverse voltage on the diode?

Peak inverse voltage is an important parameter defined as the maximum reverse bias voltage applied across the diode before entering the breakdown region. If the peak inverse voltage rating is less than the value, then breakdown may occur. For a full-wave rectifier, the diode’s peak inverse voltage is the same as the peak voltage = Vm. So, peak inverse voltage =5 volts.

3. A input of 100Sin 100 πt volt is applied to a full-wave rectifier. What is the output ripple frequency?

V= V_mSinωt

Here, ω= 100

Frequency is given as – ω/2 = 100/2 = 50 Hz.

Thus, the output frequency = 50*2 = 100 Hz.

4. What is the main application of a rectifier? Which device does the opposite operation?

A rectifier transforms the AC voltage to the DC voltage. An oscillator converts a DC voltage to AC voltage.

5. For a bridge rectifier, the input voltage applied is 20Sin100 π t. What will be the average output voltage?

Now we know that, V= V_mSinωt

V_m = 20

So, the output voltage = 2V_m / π = 2*20 / π = 12.73 volts

The output voltage is = 12.73 volts.