of 127

ANALOG CIRCUITS – I

Apr 07, 2018

Documents

Welcome message from author
Transcript
• 8/4/2019 ANALOG CIRCUITS I

1/127

DEEPAK.P

ECE

SNGCE

ANALOG CIRCUITS I

• 8/4/2019 ANALOG CIRCUITS I

2/127

RC circuits

Diode circuits

Voltage regulators

UNIT I

• 8/4/2019 ANALOG CIRCUITS I

3/127

Basics of circuit analysis

Calculate the ID,VR

0.7V

8 V

2.2 K

VD

VR

ID

• 8/4/2019 ANALOG CIRCUITS I

4/127

Basics of circuit analysis

Calculate the ID,VR

0.7V

8 V

2.2 K

VD

VR

ID

• 8/4/2019 ANALOG CIRCUITS I

5/127

Basics of circuit analysis

Calculate the ID,VR,VD

Assume that RD is Germanium Diode

8 V

2.2 K

RD

VR

ID

Low R

• 8/4/2019 ANALOG CIRCUITS I

6/127

Basics of circuit analysis

Calculate the ID,VR,VD

Assume that RD is Silicon Diode

8 V

2.2 K

RD

VR

ID

High R

• 8/4/2019 ANALOG CIRCUITS I

7/127

Diode

Diodes allow electricity to flow in only one direction.

The arrow of the circuit symbol shows the direction in which the current can

flow.

Diodes are the electrical version of a valve and early diodes were actually called

valves.

• 8/4/2019 ANALOG CIRCUITS I

8/127

Diode

• 8/4/2019 ANALOG CIRCUITS I

9/127

Diode

• 8/4/2019 ANALOG CIRCUITS I

10/127

Diode Biasing

Forward Voltage DropElectricity uses up a little energy pushing its

way through the diode, rather like a personpushing through a door with a spring.This means that there is a small voltage

across a conducting diode, it is called theforward voltage dropand is about 0.7V forall normal diodes which are made from silicon.The forward voltage drop of a diode is almost

constant whatever the current passingthrough the diode so they have a very steepcharacteristic (current-voltage graph).

• 8/4/2019 ANALOG CIRCUITS I

11/127

Diode

• 8/4/2019 ANALOG CIRCUITS I

12/127

Diode

Reverse Voltage

When a reverse voltage is applied a perfectdiode does not conduct, but all real diodesleak a very tiny current of a few A or less.

This can be ignored in most circuitsbecause it will be very much smaller thanthe current flowing in the forward direction.

However, all diodes have a maximum

reverse voltage (usually 50V or more)and if this is exceeded the diode will failand pass a large current in the reversedirection, this is called breakdown.

• 8/4/2019 ANALOG CIRCUITS I

13/127

Diode characteristics

• 8/4/2019 ANALOG CIRCUITS I

14/127

IdealDiodeForward bias

Reverse bias

R is Low

R is High

• 8/4/2019 ANALOG CIRCUITS I

15/127

RealDiodeForward bias

Reverse bias

Cell

• 8/4/2019 ANALOG CIRCUITS I

16/127

Different Diode Bias

Determine the bias condition of the diodein the following cases0V5V

5V0V

5V 0V

3V5V

5.1V5V

-3V-5V

-6V-2V

• 8/4/2019 ANALOG CIRCUITS I

17/127

Diode application

It is useful in non linear wave shaping circuits.

Commonly used circuits areClippers

Clampers.

Rectifiers

In electronics, a clipper is a device designed to prevent

the output of a circuit from exceeding a

predetermined voltage level without distorting theremaining part of the applied waveform.

• 8/4/2019 ANALOG CIRCUITS I

18/127

CLIPPING

A clipping circuit consists of linear elements likeresistors and non-linear elements like junction diodes

or transistor.

Clipping circuits are also called asSlicers, amplitude

selectors or limiters.

One of the most basic clipping circuit is thehalf-wave rectifier.

A half-wave rectifier clips either thenegative half cycle or the positive half cycleof an alternating waveform, and allows topass only one half cycle.

• 8/4/2019 ANALOG CIRCUITS I

19/127

Application of Clipping Such a circuit has great applications in

radars, digital computers and otherelectronic systems for removing unwantedportions of the input signal voltages aboveor below a specified level.

Another application is in radio-receivers forcommunication circuits where noise pulsesthat rise well above the signal amplitudeare clipped down to the desired level.

• 8/4/2019 ANALOG CIRCUITS I

20/127

Clipper Circuits

The basic components required for aclipping circuit are an ideal diode and aresistor.

In order to fix the clipping level to thedesired amount, a dc battery must also beincluded.

Different levels of clipping can be obtainedby varying the amount of voltage of the

battery and also interchanging thepositions of the diode and resistor.

04/21/12Deepak.P20

• 8/4/2019 ANALOG CIRCUITS I

21/127

Classification of CLIPPING

Classifications Of ClippersAccording to non-linear devices used,

clippers may be classified asDiode clippers andTransistor clippers.

According to biasing, the clippers may beclassified as

Unbiased clippers andBiased clippers.

• 8/4/2019 ANALOG CIRCUITS I

22/127

Classification of CLIPPING

According to configuration used theclippers may be

Series diode clippersA series combination of diode, resistor and reference supply

Parallel or shunt diode clippers

Multi-diode clippers/Combinational clippers

It consisting of several diodes, resistors and reference voltages.

• 8/4/2019 ANALOG CIRCUITS I

23/127

Classification of CLIPPING

According to level of clipping the clippersmay bePositive clippers

Negative clippers

Biased clippers and

Combination clippers

• 8/4/2019 ANALOG CIRCUITS I

24/127

Classification of CLIPPING

There are two types of clipper circuitsSeries clipping

Parallel clipping

Series clipping

In these types of circuits, the diode is connected

between the input and output voltage terminals.

Parallel clipping

In these types of circuits, the diode is connected inparallel.

• 8/4/2019 ANALOG CIRCUITS I

25/127

Positive Clipper

04/21/12Deepak.P25

• 8/4/2019 ANALOG CIRCUITS I

26/127

+VE series CLIPPING

• 8/4/2019 ANALOG CIRCUITS I

27/127

Transfer Characteristics

04/21/12Deepak.P27

Vm

• 8/4/2019 ANALOG CIRCUITS I

28/127

Negative Diode Clipper

04/21/12Deepak.P28

• 8/4/2019 ANALOG CIRCUITS I

29/127

-VE series CLIPPING

Diodes will act as an "ON/OFF switch.

• 8/4/2019 ANALOG CIRCUITS I

30/127

-VE Parallel CLIPPING

• 8/4/2019 ANALOG CIRCUITS I

31/127

Clipper circuits

04/21/12Deepak.P31

• 8/4/2019 ANALOG CIRCUITS I

32/127

Negative& Positive Diode Clipper

04/21/12Deepak.P32

• 8/4/2019 ANALOG CIRCUITS I

33/127

Biased Negative Clipper

A biased clipper comes in handy when asmall portion of positive or negative halfcycles of the signal voltage is to beremoved.

When a small portion of the negative halfcycle is to be removed, it is called a biasednegative clipper.

04/21/12Deepak.P33

• 8/4/2019 ANALOG CIRCUITS I

34/127

Biased Positive Clipper

04/21/12Deepak.P34

• 8/4/2019 ANALOG CIRCUITS I

35/127

Biased Positive Clipper and Biased Negative Clippers

04/21/12Deepak.P35

Biased Positive Clipper and Biased Negative

• 8/4/2019 ANALOG CIRCUITS I

36/127

Biased Positive Clipper and Biased Negative

Clipper

04/21/12Deepak.P36

• 8/4/2019 ANALOG CIRCUITS I

37/127

Combination Clipper

When a portion of both positive andnegative of each half cycle of the inputvoltage is to be clipped (or removed),combination clipper is employed. The

circuit for such a clipper is given in thefigure below.

04/21/12Deepak.P37

• 8/4/2019 ANALOG CIRCUITS I

38/127

Transistor Clipper

Transistor can be used to clip the I/P waveform.

Positive clipper , negative clipper, Combinational

clipper can be designed using Transistor circuit.

The practical circuit for positive and negative clippingis Transistor switching circuit.

The practical circuit for obtain Double side clipping is

Transistor amplifier circuit.

• 8/4/2019 ANALOG CIRCUITS I

39/127

Function of a Simple Switch

An OFF type switch

Lamp does not glows

No current will flow in the circuit

Lamp

• 8/4/2019 ANALOG CIRCUITS I

40/127

Function of a Simple Switch

An ON type switch

Lamp glows

Some amount of current flows in the circuit according to

the resistance.

Lamp

• 8/4/2019 ANALOG CIRCUITS I

41/127

Transistor as a Switch

Bipolar transistors can be made to operate as an"ON/OFF switch.

Because a transistor's collector current is

proportionally limited by its base current, it can be

used as a current-controlled switch.

If the circuit uses the Transistor as a Switch, then the

biasing is arranged to operate the transistor in the

"Saturation" and "Cut-off" regions.

• 8/4/2019 ANALOG CIRCUITS I

42/127

Transistor as a Switch

If we are using PNP transistor, Battery should be reversed.

Lamp

• 8/4/2019 ANALOG CIRCUITS I

43/127

Transistor Act as an OFF type switch

Transistor is biased in cutoff, lamp OFF , No current flow

• 8/4/2019 ANALOG CIRCUITS I

44/127

Cut OFF Region

Cut-off" region

Both junctions are reverse-biased.

Here the operating conditions of the transistor are

Zero input base current (Ib),

Zero output collector current (Ic)Maximum collector voltage (Vce)

Here the transistor is switched fully "OFF".

• 8/4/2019 ANALOG CIRCUITS I

45/127

Transistor Act as an ON type switch

Transistor saturated, lamp ON, Current flows

• 8/4/2019 ANALOG CIRCUITS I

46/127

Saturation Region

Saturation" region

Both junctions are Forward-biased.

Here the transistor will be biased so that the maximum

amount of base current is applied, resulting in

Maximum collector current flowMinimum collector emitter voltage

Here the transistor is switched fully "ON".

• 8/4/2019 ANALOG CIRCUITS I

47/127

Transistor Switching Circuit

Transistor switching circuit can be divided in to two

Normally ON type

Normally OFF type

In normally OFF ,transistor will be in cutoff.In normally ON ,transistor will be in saturation.

• 8/4/2019 ANALOG CIRCUITS I

48/127

O/P Characteristics of CE configuration

Soft Saturation Point

Hard

SaturationP

oint

• 8/4/2019 ANALOG CIRCUITS I

49/127

Simple Amplifier

VCC

O/PI/P

RB

RC

• 8/4/2019 ANALOG CIRCUITS I

50/127

Amplifier Operation

VCC

VCC/

(RC+RE)

Q POINT

VCEQ

ICQ

• 8/4/2019 ANALOG CIRCUITS I

51/127

Normally ON type Switch

VCC

O/PI/P

RBRC

• 8/4/2019 ANALOG CIRCUITS I

52/127

Normally ON type SwitchThe Q point of the transistor must fix in the hard

saturation/Soft Saturation point.For that ,fix VCEQ=0.2and

ICRC= VCC-VCEQ

VCC

VCC/RC

Q POINT

VCEQ

ICQ

• 8/4/2019 ANALOG CIRCUITS I

53/127

Design of Normally ON type SwitchAssume VCC,IC,

O/P Loop equationVCC=VCE+ICRC VCE sat=0.2

RC=VCC VCE sat/ IC ;

I/P Loop equation

IC= IB

VCC=5 IB RB+VBE ;

RB=VCC -VBE / 5 IB ;

• 8/4/2019 ANALOG CIRCUITS I

54/127

O/P wave form when I/P is Square wave

INPUT

OUTPUT

0.2 V

• 8/4/2019 ANALOG CIRCUITS I

55/127

O/P when I/P is Sine wave

VCC

VCC/(RC)

Q POINT

VCEQ

0.2V

• 8/4/2019 ANALOG CIRCUITS I

56/127

Normally OFF type Switch

VCC

O/P

I/P

RB

RC

• 8/4/2019 ANALOG CIRCUITS I

57/127

Normally OFF type SwitchThe Q point of the transistor must fix in the cut-off

For that ,fix VCEQ=VCC andICQ=0; To fix ICQ=0 , IB =0, So No Dc bias is applied to the base.

Practically a small negative voltage is applied to the Base.

VCC

VCC/RC

Q POINT

• 8/4/2019 ANALOG CIRCUITS I

58/127

Design of Normally OFF type SwitchAssume VCC,IC,

O/P Loop equationVCC=VCE+ICRC VCE sat=0.2

RC=VCC VCE sat/ IC ;

I/P Loop equation

IC= IB

VCC=5 IB RB+VBE ;

RB=VCC -VBE / 5 IB ;

• 8/4/2019 ANALOG CIRCUITS I

59/127

O/P wave form when I/P is Square wave

INPUT

OUTPUT

0.2V

• 8/4/2019 ANALOG CIRCUITS I

60/127

O/P when I/P is Sine wave

ICQ

VCC

VCC/(RC)

Q POINT

VCEQ

ICQ=0 VCEQ=VCC

CAPACITOR

• 8/4/2019 ANALOG CIRCUITS I

61/127

CAPACITOR

A capacitor is a device that can store electrical charge.The simplest type is a "parallel plate " Capacitor that

consists of two metal plates that are separated by an

insulating material.

Capacitor is a two-terminal device.

Capacitor has two active electrodes.Anode

Cathode

CAPACITOR

• 8/4/2019 ANALOG CIRCUITS I

62/127

CAPACITOR

• 8/4/2019 ANALOG CIRCUITS I

63/127

Charging of a Capacitor from a DC source

If we connect the two plates to each other with abattery, the free electrons is accumulated in one plate

of a capacitor. Similarly positive charges is

accumulated to the another plate.

Ch i f C it

• 8/4/2019 ANALOG CIRCUITS I

64/127

Charging of a Capacitor

If we quickly remove the wires without touching the

plates, the charge remains on the plates.Because the two plates have different charge, there is a

net electric field between the two plates.

The "capacitance" of a capacitor is stated in terms of

the amount of charge (Q) stored at a given voltage

drop (across the capacitor).

C = Q / V

C = A / d= 0 r

• 8/4/2019 ANALOG CIRCUITS I

65/127

Charging of a Capacitor from a AC source

Assume that, we connect the capacitor to an ACsource.

In the positive half cycle + ve charges were

accumulated in one plate.

• 8/4/2019 ANALOG CIRCUITS I

66/127

Charging of a Capacitor from a AC source

In the negative half cycle +ve charges wereaccumulated in the other plate.

It is similar to coupling of an AC signal.

• 8/4/2019 ANALOG CIRCUITS I

67/127

Charging wave form of a Capacitor

Clamping

• 8/4/2019 ANALOG CIRCUITS I

68/127

Clamping

The clamping circuit can shift the waveform to a

specified voltage level.

Clamping circuit actually introduces a dc level to an

AC signal.

It is also known as DC restorercircuit.

It is used in the television receiver to restore the

original dc reference voltage to the video signal.

In television system ,the dc reference levelcorresponding to thebrightness level of the picture is

not transmitted with video signal.

Clamping

• 8/4/2019 ANALOG CIRCUITS I

69/127

Clamping

A capacitorand a diode can be used to design

clamping circuits.

Clamping can be classified in to

+ve clamping-ve clamping

Biased clamping circuits can be designed to clamp a

waveform at a desired level

Problem

• 8/4/2019 ANALOG CIRCUITS I

70/127

Problem

Vi=Vm Sint

VO

Draw the O/P/ wave form when the I/P is 20 Vpp

• 8/4/2019 ANALOG CIRCUITS I

71/127

-10 V

10 V

Problem

• 8/4/2019 ANALOG CIRCUITS I

72/127

Problem

Vi=Vm Sint

VO

Draw the O/P/ wave form when the I/P is 20 Vpp and it

contains a DC voltage of 2V

• 8/4/2019 ANALOG CIRCUITS I

73/127

2V

10 V

-10 V

Simple Clamping

• 8/4/2019 ANALOG CIRCUITS I

74/127

SimpleClamping

V

+-Vi=Vm Sint

VO

Battery

• 8/4/2019 ANALOG CIRCUITS I

75/127

V

Vm+V

Vm-V

Simple Clamping

• 8/4/2019 ANALOG CIRCUITS I

76/127

SimpleClamping

Vm

Vi=Vm Sint

VO

+-

• 8/4/2019 ANALOG CIRCUITS I

77/127

-V

Vm-V

-Vm-V

Simple Diode Clamping

• 8/4/2019 ANALOG CIRCUITS I

78/127

SimpleDiodeClamping

Vm

In negative half cycle ;Vo=vi+Vm=Vm Sint+Vm

+ -Vi=Vm Sint

VO

Capacitor

Simple Diode Clamping

• 8/4/2019 ANALOG CIRCUITS I

79/127

SimpleDiodeClamping

Vm

Simple Diode Clamping

• 8/4/2019 ANALOG CIRCUITS I

80/127

SimpleDiodeClamping

VmVm

O/P when I/P is square wave

• 8/4/2019 ANALOG CIRCUITS I

81/127

O/P when I/P is square wave

Vm+Vm

Simple Diode Clamping

• 8/4/2019 ANALOG CIRCUITS I

82/127

SimpleDiode Clamping

Vm

+-

In the 2nd

positive half cycle;Vo=Vi-Vm=Vm Sint-Vm

Vi=Vm Sint

VO

Capacitor

O/P when I/P is square wave

• 8/4/2019 ANALOG CIRCUITS I

83/127

O/P when I/P is square wave

Vm+Vm

O/P when I/P is square wave

• 8/4/2019 ANALOG CIRCUITS I

84/127

O/P when I/P is square wave

Vm+Vm

Problem

• 8/4/2019 ANALOG CIRCUITS I

85/127

Problem

Vm

Vi=Vm Sint

VO

+

-

The I/p signal with 24 Vpp is applied to a clamper circuit. Sketch the O/P wave

form

Problem

• 8/4/2019 ANALOG CIRCUITS I

86/127

Problem

Vm

VO

+

-

The I/p signal with 24 Vpp is applied to a clamper circuit. Sketch the O/P wave

form

Positive Clamping

• 8/4/2019 ANALOG CIRCUITS I

87/127

Positive Clamping

Vm

+

-

Draw the o/p wave form

VO

O/P when I/P is square wave

• 8/4/2019 ANALOG CIRCUITS I

88/127

O/P when I/P is square wave

Vm+Vm

Negative Clamping

• 8/4/2019 ANALOG CIRCUITS I

89/127

Negative Clamping

Vm

+

-

Draw the o/p wave form

VO

Biased Clamper

• 8/4/2019 ANALOG CIRCUITS I

90/127

Biased Clamper

Vm

Vi=Vm Sint

VO

+

-

The I/p signal with 24 Vpp is applied to a clamper circuit. Sketch the O/P wave

form

-

+5V

Biased Clamper

• 8/4/2019 ANALOG CIRCUITS I

91/127

Biased Clamper

Biased Clamper

• 8/4/2019 ANALOG CIRCUITS I

92/127

Biased Clamper

Biased Clamper

• 8/4/2019 ANALOG CIRCUITS I

93/127

Biased Clamper

Biased Clamper

• 8/4/2019 ANALOG CIRCUITS I

94/127

Biased Clamper

• 8/4/2019 ANALOG CIRCUITS I

95/127

RC Circuits

An RC circuit is simply a circuit with avoltage source (battery) connected inseries with a resistor and a capacitor.

A resistor-capacitor circuit (RC circuit), or

RC filter or RC network, is an electric circuitcomposed of resistors and capacitorsdriven by a voltage or current source. The1st order RC circuit, composed of one

resistor and one capacitor, is the simplestexample of an RC circuit.

04/21/12Deepak.P95

• 8/4/2019 ANALOG CIRCUITS I

96/127

RC Circuits

04/21/12Deepak.P96

• 8/4/2019 ANALOG CIRCUITS I

97/127

RC Circuits

04/21/12Deepak.P97

As with circuits made up simply ofresistors, electrical currents can flow in thisRC circuit, with one modification. A batteryconnected in series with a resistor will

produce a constant current. The samebattery in series with a capacitor willproduce a time varying current, whichdecays gradually to zero. If the battery is

removed and the circuit reconnectedwithout the battery, a current will flow (fora short time) in the opposite direction asthe capacitor "discharges". A measure of

how long these transient currents last in a"

• 8/4/2019 ANALOG CIRCUITS I

98/127

RC Circuits

04/21/12Deepak.P98

Time ConstantThe time constant of an RC circuit is the

product of its resistance and capacitance.For R in ohms and C in farads, the time

constant tis in seconds.T = RC

The range of frequencies that the filterpasses is called its bandwidth. The point at

which the filter attenuates the signal to halfits unfiltered power is termed its cutofffrequency. This requires that the gain ofthe circuit be reduced to

• 8/4/2019 ANALOG CIRCUITS I

99/127

RC Circuits

04/21/12Deepak.P99

• 8/4/2019 ANALOG CIRCUITS I

100/127

RC Circuits

04/21/12Deepak.P100

• 8/4/2019 ANALOG CIRCUITS I

101/127

RC Circuits

High Pass FilterA High Pass Filter or HPF, is the exact opposite to that

of Low Pass filter circuit, as now the two components

have been interchanged with the output signal (Vout)

being taken from across the resistor.Where the low pass filter only allowed signals to pass

below its cut-off frequency point, c, the passive high

pass filter circuit as its name implies, only passes

signals above the selected cut-off point, c eliminatingany low frequency signals from the waveform.

04/21/12Deepak.P101

High Pass Filter

• 8/4/2019 ANALOG CIRCUITS I

102/127

04/21/12Deepak.P102

In this circuit arrangement, the reactance of the capacitor is very high at

low frequencies so the capacitor acts like an open circuit and blocks any

input signals at Vin until the cut-off frequency point (c) is reached. Above

this cut-off frequency point the reactance of the capacitor has reduced

sufficiently as to now act more like a short circuit allowing all of the input

signal to pass directly to the output as shown below in the High PassFrequency Response Curve.

High Pass Filter

• 8/4/2019 ANALOG CIRCUITS I

103/127

04/21/12Deepak.P103

High Pass Filter

• 8/4/2019 ANALOG CIRCUITS I

104/127

04/21/12Deepak.P104

The circuit gain, Av which is given as Vout/Vin (magnitude) and is

calculated as:

Cut-off Frequency and Phase Shift

High Pass Filter

• 8/4/2019 ANALOG CIRCUITS I

105/127

High pass filter stages can be cascadedtogether to form a second-order (two-pole)filter as shown.

04/21/12Deepak.P105

High Pass Filter

• 8/4/2019 ANALOG CIRCUITS I

106/127

A very common application of a passivehigh pass filter, is in audio amplifiers as acoupling capacitor between two audioamplifier stages and in speaker systems todirect the higher frequency signals to thesmaller "tweeter" type speakers whileblocking the lower bass signals or are alsoused as filters to reduce any low frequencynoise or "rumble" type distortion. Whenused like this in audio applications the highpass filter is sometimes called a "low-cut",or "bass cut" filter.

04/21/12Deepak.P106

High Pass Filter

• 8/4/2019 ANALOG CIRCUITS I

107/127

RC Differentiator

04/21/12Deepak.P107

RC Differentiator

• 8/4/2019 ANALOG CIRCUITS I

108/127

Each cycle of the square wave input waveformproduces two spikes at the output, one positive and one

negative and whose amplitude is equal to that of the

input. The rate of decay of the spikes depends upon the

time constant, (RC) value of both components, (t = R xC) and the value of the input frequency. The output

pulses resemble more and more the shape of the input

signal as the frequency increases.

04/21/12Deepak.P108

RC Differentiator

• 8/4/2019 ANALOG CIRCUITS I

109/127

From theory we know that the voltageacross the resistor in an RC circuit is givenby:

Charging: vR = Vp e- tRC

Discharging: vR = - Vp e- tRC

04/21/12Deepak.P109

RC Integrator

• 8/4/2019 ANALOG CIRCUITS I

110/127

From theory we know that the voltageacross the capacitor in an RC circuit isgiven by:

Charging: vc = Vp (1 e-t/RC)Discharging: vc = Vp e- tRC

04/21/12Deepak.P110

RC Integrator

• 8/4/2019 ANALOG CIRCUITS I

111/127

04/21/12Deepak.P111

RECTIFIERS

• 8/4/2019 ANALOG CIRCUITS I

112/127

RECTIFIERS

A rectifier is an electrical device that convertsalternating current (AC) to direct current (DC).

Rectifiers have many uses including as components of

power supplies and as detectors of radio signals.

Rectifiers may be made of solid state diodes, vacuumtube diodes, mercury arc valves, and other

components.

RECTIFIERS(C td )

• 8/4/2019 ANALOG CIRCUITS I

113/127

RECTIFIERS(Contd..)

Rectifiers can be divided in to twoHalf wave Rectifiers

Full wave Rectifiers

In half wave rectification, either the positive or

negative half of the AC wave is passed, while the otherhalf is blocked.

Half-wave rectification can be achieved with a single

diode in a one phase supply, or with three diodes in a

three-phase supply.

HALF WAVE

• 8/4/2019 ANALOG CIRCUITS I

114/127

RECTIFIERS(Contd..)

Full WAVE RECTIFIERS

• 8/4/2019 ANALOG CIRCUITS I

115/127

Full WAVE RECTIFIERS

• 8/4/2019 ANALOG CIRCUITS I

116/127

Full WAVE RECTIFIERS

• 8/4/2019 ANALOG CIRCUITS I

117/127

A full-wave rectifier converts the whole ofthe input waveform to one of constantpolarity (positive or negative) at its output.Full-wave rectification converts both

polarities of the input waveform to DC(direct current), and is more efficient.However, in a circuit with a non-centertapped transformer, four diodes are

required instead of the one needed for half-wave rectification. Four rectifiers arrangedthis way are called a diode bridge or bridgerectifier.

Bridge RECTIFIERS

• 8/4/2019 ANALOG CIRCUITS I

118/127

g

Regulated Power Supply

• 8/4/2019 ANALOG CIRCUITS I

119/127

g pp y

There are many types of power supply.Most are designed to convert high voltageAC mains electricity to a suitable lowvoltage supply for electronics circuits and

other devices. A power supply can bybroken down into a series of blocks, each ofwhich performs a particular function.

Regulated Power Supply

• 8/4/2019 ANALOG CIRCUITS I

120/127

g pp y

Each of the blocks is described in more detail below:

Transformer - steps down high voltage AC mains to low voltage AC.

Rectifier - converts AC to DC, but the DC output is varying.

Smoothing - smoothes the DC from varying greatly to a small ripple.

Regulator - eliminates ripple by setting DC output to a fixed voltage.

Transformer only

Transformer + Rectifier

Transformer + Rectifier + Smoothing

Transformer + Rectifier + Smoothing + Regulator

Zener Diode

• 8/4/2019 ANALOG CIRCUITS I

121/127

Zener Diode

04/21/12Deepak.P121

A Zener diode is a type of diode that permits current not only in

the forward direction like a normal diode, but also in the reverse

direction if the voltage is larger than the breakdown voltage

known as "Zener knee voltage" or "Zener voltage". The device

was named after Clarence Zener, who discovered this electricalproperty.

Zener Regulator

• 8/4/2019 ANALOG CIRCUITS I

122/127

Zener Regulator

Zener diodes are widely used as voltagereferences and as shunt regulators toregulate the voltage across small circuits.When connected in parallel with a variable

voltage source so that it is reverse biased,a Zener diode conducts when the voltagereaches the diode's reverse breakdownvoltage. From that point on, the relatively

low impedance of the diode keeps thevoltage across the diode at that value.

04/21/12Deepak.P122

Zener Regulator

• 8/4/2019 ANALOG CIRCUITS I

123/127

Zener Regulator

A Zener diode is a PN junction that hasbeen specially made to have a reversevoltage

breakdown at a specific voltage. Its

characteristics are otherwise very similar tocommon

diodes. In breakdown the voltage acrossthe Zener diode is close to constant over a

widerange of currents thus making it useful as a

shunt voltage regulator.

04/21/12Deepak.P123

Zener characteristic

• 8/4/2019 ANALOG CIRCUITS I

124/127

Zener characteristic

04/21/12Deepak.P124

Zener Regulator

• 8/4/2019 ANALOG CIRCUITS I

125/127

Zener Regulator

04/21/12Deepak.P125

Zener Regulator

• 8/4/2019 ANALOG CIRCUITS I

126/127

Zener Regulator

04/21/12Deepak.P126

Fixed IC voltage Regulators

• 8/4/2019 ANALOG CIRCUITS I

127/127

Fixed IC voltage Regulators

Voltage Regulator (regulator), usuallyhaving three legs, converts varying inputvoltage and produces a constant regulatedoutput voltage. They are available in a