1. per
Clam
& er
Clipp 1

2. Topics t o b e discu ssed • What is a Clipper Circuit ?
• General characteristic of a double clipper.
• Series negative clipper.
• Processing by series negative clipper.
• Series Biased Clippers.
• Guidelines to Solve.
• Numerical Examples.
Oscillators By S.M.Mehzabeen 2

3. Clippers • A circuit that clips off or removes a portion of the
input signal.
• A clipper can process any type of signal.
Oscillators By S.M.Mehzabeen 3

4. SINGLE CLIPPERS – Positive Negative
There can be single
clippers : – –
Two
Positive
Negative
categories :
Series – Diode and load in series. Parallel – Diode and load in parallel.
Oscillators By S.M.Mehzabeen 4

5. SINGLE CLIPPERS The circuit The transfer characteristics 5 2014-12-24
Oscillators By S.M.Mehzabeen 5

6. P rocessin g b y series n egat iv e clipper Square wave Triangular
• This clipper is like
a half-wave rectifier.
Oscillators By S.M.Mehzabeen 6

7. R ect an gu lar w av e or Squ are w av e ? •
Ans. Both are same. Usually, we
call it a
square
wave.
Oscillators By S.M.Mehzabeen 7

8. What happens if the diode in a half-wave
rectifier is reversed ?
Ans. It still remains a half-wave
rectifier,
but it
now
works as
a positive
clipper.
Oscillators By S.M.Mehzabeen 8

9. Series Biased Clippers • Bias means applying a circuit. dc voltage
to change the dc level of a
Oscillators By S.M.Mehzabeen 9

10. Plot the waveshape of vo for given input.
Guidelines to Solve •
Determine the transition level at which the diode
turns ON.
With diode ON, find relation between vo and vi. • •
Draw the transfer characteristic of the clipper. •
Plot the waveshape of vo for given input.
Oscillators By S.M.Mehzabeen 10

11. • When diode is ON, vo = vi – VB.
We find
• Diode is ON for vi > VB.
that
• Therefore,
vi(tr) =
VB.
• When diode is ON, vo = vi –
• When diode is OFF, vo = 0.
VB.
• Plot the transfer characteristic
of the clipper.
Oscillators By S.M.Mehzabeen 11

12. Output... 12 Now, draw the output. 2014-12-24
Oscillators By S.M.Mehzabeen 12

13. Example 1 • Determine the output waveform for the clipper circuit, if
input is a
sinusoidal
wave of
peak
value 15 V.
Oscillators By S.M.Mehzabeen 13

14. vd  0 V id  0 A; vo  vi ( tr ) id RL  0 vi ( tr ) Solution and
• The direction of the diode suggests that it will be ON for positive values of vi.
• At transition level,
vd  0 V
and
id  0 A;
so that
 0 
vo 
vi ( tr )
id RL  0
 3 V
Writing KVL,
vi ( tr )
 3
Oscillators By S.M.Mehzabeen 14

15. vo  vi  3 Solution • After diode is ON, 15 2014-12-24
Oscillators By S.M.Mehzabeen 15

16. Output... Draw the output. Transfer characteristic 16 2014-12-24
Oscillators By S.M.Mehzabeen 16

17. Example 2 • Determine the output waveform for the clipper circuit of1, if
its
input is as
follows
Oscillators By S.M.Mehzabeen 17

18. vi vi = Solution Problem is simpler. Only two levels : = +15 V and -5
Oscillators By S.M.Mehzabeen 18

19. Solution output. Now, you can draw the 19 2014-12-24
Oscillators By S.M.Mehzabeen 19

20. swing of vi is 2. Total swing of vo is 18 – 0 SINGLE CLIPPERS
Note that
1. Total
15 –
swing of vi is
(-5) = 20 V.
2. Total swing of vo is 18 – 0
= 18 V.
3. Clipper circuit clipped off 2 V, and raised
the
dc level by 3 V.
Oscillators By S.M.Mehzabeen 20

21. Clamper • A circuit that places either the positive or negative peak
of a signal at a desired D.C level is known as a clamping
circuit.
• A clamping circuit introduces (or restores) a D.C level
to an A.C signal. Thus a clamping
as D.C restorer, or D.C reinserted stabilizer.
circuit is also
or a baseline
known
Oscillators By S.M.Mehzabeen 21

22. • Negative clamping occurs when positive peaks raised or
General types of clamping
• Positive clamping occurs when negative peaks raised or
clamped to ground or on the zero level In other words, it
pushes the signal upwards so that negative peaks fall on
zero level.
• Negative clamping occurs when positive peaks raised or
the
clamped to
pushes the on the zero
ground or on the zero level In
signal downwards so that the level
other words, it
positive peaks
fall
Oscillators By S.M.Mehzabeen 22

23. Clamping
Waveform
Oscillators By S.M.Mehzabeen 23

24. POSITIVE CLAMPER
• Consists of a diode and a capacitor the clamper output is
taken
across
the
load
resistance R.
Oscillators By S.M.Mehzabeen 24

25. POSITIVE CLAMPER
• During the negative half cycle of the input voltage, the
diode conducts heavily and behaves as a closed switch At the negative peak, the capacitor is charged to maximum voltage V slightly beyond the negative peak, the diode is shunt off and the capacitor charged to Vm behaves as a battery during the positive half cycle of the input signal.
Oscillators By S.M.Mehzabeen 25

26. POSITIVE CLAMPER
• During the negative half cycle of the input voltage, the
diode conducts heavily and behaves as a closed switch At the negative peak, the capacitor is charged to maximum voltage V slightly beyond the negative peak, the diode is shunt off and the capacitor charged to Vm behaves as a battery during the positive half cycle of the input signal.
Oscillators By S.M.Mehzabeen 26

27. POSITIVE CLAMPER
• The diode is reversed biased and the output voltage will
be equal to Vm + V this gives positive
clamped
voltage
and is
called
positive
clamper
circuit.
Oscillators By S.M.Mehzabeen 27

28. Positive
clamper
with
bias
Oscillators By S.M.Mehzabeen 28

29. Positive clamper with bias
• Biased clamper circuit operates in exactly the same
manner as unbiased clampers.
• The different is only that a dc bias voltage is add in series
with the diode and resistor.
• A biased clamper means that the clamping can be
done at any voltage level other than zero.
Oscillators By S.M.Mehzabeen 29

30. Negative CLAMPER
• Negative clamper during the positive half cycle of the
input
signal,
the
capacitor is
charged to
Vm,
with the
polarity R.
shown in
Fig . is
taken
across
the
load
resistance
Oscillators By S.M.Mehzabeen 30

31. Negative
CLAMPER
Oscillators By S.M.Mehzabeen 31

32. Negative Clampers • Voltage across the capacitor is opposing the input
voltage V. This gives negative clamped
voltage
and is
called
negative
clamper
circuit.
Oscillators By S.M.Mehzabeen 32