This document discusses clipper circuits, which are wave shaping circuits that remove parts of an input signal above or below a reference value. There are two main types of clippers: positive clippers, which clip off positive parts of the signal above the reference value, and negative clippers, which clip off negative parts below the reference value. Clipper circuits use diodes and op-amps to clip portions of the waveform and are commonly used in applications like signal separation, limiting noise spikes, waveform generation, and voltage protection.

1. Contents
 Introduction
 What is clippers ?
 Types of clippers
 Positive clippers
 Negative clippers
 Application of clippers
 Summary

2. Introduction
 Wave shaping circuits are the electronic circuits, which
produce the desired shape at the output from the applied
input wave form. These circuits perform two functions −
 Attenuate the applied wave
 Alter the dc level of the applied wave.
 There are two types of wave shaping circuits:
Clippers and Clampers.
In this topic, we will learn in detail about clippers.

3. What is clippers ?
A clipper is an electronic circuit
that produces an output by
removing a part of the input
above or below a reference
value. That means, the output
of a clipper will be same as
that of the input for other than
the clipped part. Due to this,
the peak to peak amplitude of
the output of a clipper will be
always less than that of the
input.

4. Coun.--
 Clippers circuit is known as a wave shaping circuit. Wave
shaping circuits are commonly used in digital computer
and communications such as TV and FM receivers. Wave
shaping techniques including limiting, clipping and
clamping. In op-amp Clipper circuits a rectifier diode may
be used to clip off certain portion of the input signal to
obtain a desired output waveshape. An op-amp half wave
rectifier and an absolute-value output circuit use diodes
to remove or modify certain portion of the input
waveform
 the diode works as an ideal diode (switch) because, when
on, the voltage drop across the diode is divided by the
open-loop gain of the op-amp. On the other hand, when
reverse biased (off), the diode is an open circuit.

5. Types of Clippers
 Clippers can be classified into
the following two types based
on the clipping portion of the
input.
 Positive Clipper
 Negative Clipper

6. Positive Clipper
 A circuit that removes
positive parts of the input
signal can be formed by
using an op-amp with a
rectifier diode. The clipping
level is determined by the
reference voltage Vref,
which should less than the
i/p range of the op-amp
(Vref < Vin). The Output
voltage has the portions of
the positive half cycles
above Vref clipped off.

7. The circuit works as
follows:
During the positive half cycle of
the input, the diode D1 conducts
only until Vin = Vref. This happens
because when Vin <Vref, the output
volts V0 of the op-amp becomes
negative to device D1 into
conduction when D1 conducts it
closes feedback loop and op-amp
operates as a voltage follower.
(i.e.) Output V0 follows input until
Vin = Vref.

8. Count.
When Vin > Vref => the
V0 becomes +ve to derive D1 into
off. It opens the feedback loop
and op- amp operates open
loop. When Vin drops below
Vref (Vin<Vref) the o/p of the op-
amp V0 again becomes –ve to
device D1 into conduction. It
closes the feedback path. (o/p
follows the i/p).
Thus diode D1 is on for
vin<Vref (o/p follows the i/p) and
D1 is off for Vin>Vref.

9. Count.
 The op-amp alternates
between open loop (off) and
closed loop operation as the
D1 is turned off and on
respectively. For this reason
the op-amp used must be
high speed and preferably
compensated for unity gain.
 Ex: for high speed op-amp HA
2500, LM310, μA 318.

10. Negative Clipper:
 The positive clipper is
converted into a –ve clipper
by simply reversing diode
D1 and changing the polarity
of Vref voltage. The negative
clipper clips off the –ve
parts of the input signal
below the reference
voltage.

11. Count.
 Diode D1 conducts -> when
Vin > -Vref and therefore during
this period o/p volt V0 follows
the i/p volt Vin. The –ve portion
of the output volt below –Vref is
clipped off because (D1 is off)
Vin<-Vref. If –Vref is changed to
–Vref by connecting the
potentiometer Rp to the +Vcc,
the V0 below +Vref will be clipped
off. The diode D1 must be on for
Vin > Vref and off for Vin.

12. more
exmples:
 Find the output
waveform for when
Vin < Vref
Explanation: The
negative portion
of the output
voltage below -
Vref is clipped off
because, diode
will be in off
condition when
Vin < Vref.

13. Application of
clippers:
 They are frequently used for
the separation of synchronizing
signal from the composite
picture signals.
 The excessive noise spikes
above a certain level can be
limited or clipped in FM
transmitters by using the series
clippers.
 For the generation of
new waveforms or shaping the
existing waveform, clippers are
used.

14. Application of
Clippers:
 The typical application of diode
clipper is for the protection of
transistor from transients, as a
freewheeling diode connected in
parallel across the inductive load
 Frequently used half wave rectifier
in power supply kits is a typical
example of a clippers .It
clips either positive or negative half
wave of the input.
 Clippers can be used as voltage
limiters and amplitude selectors.

15. Summary:
 Clipper circuits are the circuits that clip off or removes a portion of an
input signal, without causing any distortion to the remaining part of the
waveform.
 Clippers
 Positive Clippers Negative Clippers
 D1 is on for vin<Vref (o/p follows the i/p)
and D1 is off for Vin>Vref.
(D1 is off) Vin<-Vref.

16. References:
 Op-Amps and
linear integrated
circuits by
Ramakant A.
Gayakwad
 Goggle searches.