Clipper and clamper circuits

1. Clipper And
Clamper Circuits
By Unsa Shakir

2. What are clipper circuits?
• Clippers Circuits are used to remove the part of a signal
that is above or below some defined reference level.
• One of the simple example of a clipper is the half-wave
rectifier – that circuit basically cut off everything at the
reference level of zero and let only the positive-going or
negative-going portion of the input waveform.
• Clipping circuits (also known as limiters, amplitude selector
or slicers)
• Depending on the orientation of the diode, the positive or
negative region of the input signal is “clipped” off.

3. Types of Clippers Circuits
Unbiased
Clipper Circuit
Unbiased
Positive
clipper
Unbiased
Negative
clipper
Biased clipper
circuit
Biased
positive
clipper
Biased
negative
clipper
Clipper series
circuits

4. Unbiased positive Clippers
 Positive clippers are used to clip positive portions of the input signal and allow the
negative portions of the signal to pass through
• Figure below shows the input and output signal along with the positive clipper. The
positive cycle is completely clipped off by the clipper.
• During the positive half cycle of the input waveform, the diode ‘D’ is reverse biased,
which maintains the output voltage at 0 Volts. This causes the positive half cycle to be
clipped off. During the negative half cycle of the input, the diode is forward biased and so
the negative half cycle appears across the output.

5. Unbiased Negative clippers
Negative clippers are used to clip Negative portions of the input signal and allow the
positive portions of the signal to pass through
Figure shows the input and output signal along with the negative
clipper. The negative cycle is completely clipped off by the clipper.
The diode in forward biased configuration can be modelled as an close switch. This is
indicated in the figure. As the diode acts as closed switch, current flows through the
load and hence output appears across the load. This is the reason why the negative cycle
is completely clipped off.

6. Biased positive clipper
 As shown earlier, we saw that the clipping of the signal
takes place as soon as the input signal goes positive. If we
want to change/adjust the clipping level of AC voltage,
then external biasing voltage must be used. The figure
given below shows a biased (series) clipper.

7. Working:
• A biased clipper comes in handy when a small portion of positive or negative half
cycles of the signal voltage is to be removed. When a small portion of the positive half
cycle is to be removed, it is called a biased positive clipper.
• It is similar to the series positive clipper in addition to a negative reference voltage in
series with a resistor; and here, during the positive half cycle, the output appears across
the resistor as a negative reference voltage. During the negative half cycle, the output is
generated after reaching a value greater than the negative reference voltage
• Instead of negative reference voltage a positive reference voltage is connected to obtain
series positive clipper with a positive reference voltage. During the positive half cycle,
the reference voltage appears as an output across the resistor, and during the negative
half cycle, the entire input appears as output across the resistor.

8. Biased negative Clipper
 As shown earlier, we saw that the clipping of the signal
takes place as soon as the input signal goes negative. If we
want to change/adjust the clipping level of AC voltage, then
external biasing voltage must be used. The figure given
below shows a biased (series) clipper.

9. Working:
• A biased clipper comes in handy when a small portion of positive or negative half cycles of
the signal voltage is to be removed. When a small portion of the negative half cycle is to be
removed, it is called a biased negative clipper.
• Series negative clipper with positive reference voltage is similar to the series negative
clipper, but in this a positive reference voltage is added in series with the resistor. During the
positive half cycle, the diode start conducting only after its anode voltage value exceeds the
cathode voltage value.
• The series negative clipper with a negative reference voltage is similar to the series negative
clipper with positive reference voltage, but instead of positive Vr here a negative Vr is
connected in series with the resistor, which makes the cathode voltage of the diode as
negative voltage. Thus during the positive half cycle, the entire input appears as output
across the resistor, and during the negative half cycle, the input appears as output until the
input value will be less than the negative reference voltage

10. Clamper circuit
• A clamper is an electronic circuit that changes the DC level
of a signal to the desired level without changing the shape of
the applied signal. In other words, the clamper circuit moves
the whole signal up or down to set either the positive peak or
negative peak of the signal at the desired level.
• A clamper circuit is also called as a Level Shifter.
• Clamper circuits consist of energy storage elements like
capacitors. A simple clamper circuit comprises of a
capacitor, a diode, a resistor and a dc battery if required.

11. Types Of Clamper Circuits
• The direction of the diode in the clamping circuit determines
the clamper circuit type.
• The operation of a clamping circuit is mainly based on the
switching time constants of the capacitor. However,
capacitor in the circuit charges through the diode and
discharges through the load.
1. Negative clamper
2. Positive clamper

12. Negative Clamper
• The Negative Clamping circuit consists of a diode connected in
parallel with the load.
• The capacitor used in the clamping circuit can be chosen such
that it must charge very quickly and it should not discharge
very drastically. The anode of the diode is connected to the
capacitor and cathode to the ground.
• This type of clamping circuit shifts the input waveform in a
negative direction, as a result the waveform lies below a DC
reference voltage

13. • During the positive half cycle of the input, the diode is in
forward bias and as the diode conducts the capacitor charges
very quickly.
• During the negative half cycle of the input, the diode will be
in reverse bias and the diode will not conduct, the output
voltage will be equal to the sum of the applied input voltage
and the charge stored in the capacitor during reverse bias.
The output waveform is same as input waveform, but shifted
below 0 volts.

14. Positive Clamper
• The circuit of the positive clamper is similar to the negative
clamper but the direction of the diode is inverted in such a
way that the cathode of the diode is connected to the
capacitor.
• This type of clamping circuit shifts the input waveform in a
positive direction, as a result the waveform lies above a DC
reference voltage.
• A Clamping circuit restores the DC level. When a negative
peak of the signal is raised above to the zero level, then the
signal is said to be positively clamped.

15. • During the positive half wave cycle, output voltage of the
circuit will be the sum of applied input voltage and the
charge stored at capacitor.
• During the negative half wave cycle, the diode starts to
conduct and charges the capacitor very quickly to its
maximum value. The output waveform of the positive
clamper shifts towards the positive direction above the 0
volts