l8 clipper clamper

8/9/2019 L8 Clipper Clamper

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• Rectifcation – transorming AC signalinto a signal with one polarity

– Hal wave rectifer

Recall Lecture 6

• Full Wave Rectifer – Center tapped

– ridge

• Rectifer parameters

– !uty Cycles

– "ea# $nverse %oltage &"$%'



Clipper and ClamperClipper and Clamper

CircuitsCircuits



Clippers● Clipper circuits, also called limiter circuits, are used to eliminate

portion of a signal that are above or below a specified level – clip value.

● The purpose of the diode is that when it is turn on, it provides the clip

value

● Clip value = V’. To find V’, use KV at !

● The e"uation is # V’ – V$ % Vγ = & V’ = V$ ' Vγ

Then, set the conditions

(f Vi > V’, what happens) diode conducts, hence Vo = V’

(f Vi < V’, what happens) diode off, open circuit, no current flow, Vo = Vi

L1

Vi

%( ) % * %



For the circuit shown +elow s#etch the waveorm o theoutput voltage, %out- .he input voltage is a sine wave

where %in ) /0 sin ωt- Assume %γ ) 0-1 %

23A4"L2



Parallel Based Clippers

*ositive and negative clipping can be performed simultaneousl+

b+ using a double limiter or a parallel-based clipper .

The parallel%based clipper is designed with two diodes and two

voltage sources oriented in opposite directions.

This circuit is to allow clipping to occur during both c+clesnegative and positive



Clipper – !iode in 5eries

"ro+lem -//Figure "-//&a' shows the input voltage o the circuit as shownin Figure "-//&+'- "lot the output voltage %o o these circuits i

%γ ) 0-1 %

P3.11(a) P3.11(b)



Clampers● Clamping shifts the entire signal voltage

b+ a -C level.

Consider, the sinusoidal input voltage

signal, v I .

!st &&, the capacitor is charged up to

the pea/ value of Vi which is VM.

Then, as Vi moves towards the –ve

c+cle,

the diode is reverse biased.

(deall+, capacitor cannot discharge,

hence Vc = V0

$+ KV, we get

NOTE# The input signal is shifted b+ a dc

level and that the pea/%to%pea/ value is

the same



Clampers

STEP 1# Knowing what value that the capacitor is charged to. Ad !r"m

the p"larit# "! the di"de, we /now that it is charged during positive

c+cle. 1sing KV,

V$ % V& ' VS ( ) V$ ( VM ' V&

STEP *# 2hen the diode is reversed biased and VC is alread+ a constant

value

VO ' VS % V$ ( ) VO ( VS ' V$.

●

3 clamping circuit that includes an independent voltage sourceV

B.Pea+ ,alue VM



23A4"L2 – clampers with idealdiodeFor the circuit shown in fgure +elow, s#etchthe waveorms o the output voltage, %out-

.he input voltage is a sine wave where %in )

70 sin ωt- Assume ideal diodes-

%in



8ideal9

C

+

Vo

-5V

+

Vi

-

Vi

t

-10

10

.he diode is a non8ideal with %γ ) 0-1%

Step 1: VC + V - VB – Vi = 0 VC = 10 + 5 – 0.7 = 14.3VStep : V! – Vi + VC = 0 V! = Vi – 14.3-

-4.3

-4.3

-14.3

l8 clipper clamper

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