This document discusses op-amp clipper circuits. It begins by introducing op-amps and their applications. It then defines a clipper as a circuit that prevents an output from exceeding a voltage level without distorting the waveform. The document discusses positive and negative clipper circuits using op-amps and diodes. It provides examples of clipped waveforms and describes applications of clipper circuits such as protecting radio transmitters and integrated circuits.

1. By
Bhavita Modi
Integrated Circuits and Applications
EC 204

2. A nail clipper or a nail cutter is a perfect introduction to
the topic of my presentation.
We all are very well familiar with the working of a nail
clipper. This will form the base of our discussion.

3. CONTENTS
• What is an op-amp?
• Clippers
• Positive Clippers
• Negative Clippers
• Practical application of clippers
• Other applications of clippers
• Reference

5. Op-amps are among the most widely used electronic
devices today, being used in a vast array of consumer,
industrial, and scientific devices. Many standard IC op-amps
cost only a few cents in moderate production volume;
however some integrated or hybrid operational amplifiers
with special performance specifications may cost over $100
US in small quantities. Op-amps may be packaged as
components, or used as elements of more complex
integrated circuits.
We will discuss the application of op-amp as a clipper.
What is an op-amp?

6. In electronics, a clipper is a device
designed to prevent the output of a
circuit from exceeding a
predetermined voltage level without
distorting the remaining part of the
applied waveform.
A clipper circuit is known as a wave
shaping circuit. Waveshaping circuits
are commonly used in digital
computers and communication
such as TV and FM receiver.
Waveshaping technique include
clipping and clamping.
In op-amp clipper circuits a rectifier diode
may be used to clip off a certain portion
of the input signal to obtain a desired o/p
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.
When OFF(reverse biased) , the diode is
an open circuit.
CLIPPERS

7. POSITIVE CLIPPERS
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 be 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.

8. 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.
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 closed the f/b. (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. 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.

9. PRACTICAL OUTPUT

10. NEGATIVE CLIPPERS
The positive clipper is
converted into a
negative clipper by
simply reversing diode
D1 and changing the
polarity of Vref voltage.
The negative clipper
clips off the negative
parts of the input signal
below the reference
voltage.

11. The circuit works as follows:
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. PRACTICAL OUTPUT

13. A PRACTICAL APPLICATION OF CLIPPER CIRCUITS
Clipper prevents over driving radio transmitter by voice peaks.

14. A practical application of a clipper is to prevent an amplified
speech signal from overdriving a radio transmitter in above
figure. Over driving the transmitter generates spurious radio
signals which causes interference with other stations. The
clipper is a protective measure. A sine wave may be squared
up by overdriving a clipper.
Another clipper application is the protection of exposed
inputs of integrated circuits. For example, CMOS IC's use 0V
and +5 V. Analog amplifiers might use ±12V for the V1 and V2
sources.

15. Clippers find several applications, such as :
•They are frequently used for the separation of synchronizing signals 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.
•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 clipper. It clips either positive or negative half wave of the input.
•Clippers can be used as voltage limiters and amplitude selectors.

16. REFERENCES:
• Op-Amps and linear integrated circuits
by Ramakant A. Gayakwad
• Google Searches