Clamping Circuit and Clipping Circuit, Principle of Operation of Clamping Circuit, Biased positive clamping circuit, Biased negative clamping circuit, Classification of Clipping Circuit, Clipping Circuit, Zener Diode as a Peak Clipper, Application of Clipper. ,

1. Presented by
Dr. R. RAJA, M.E., Ph.D.,
Assistant Professor, Department of EEE,
Muthayammal Engineering College, (Autonomous)
Namakkal (Dt), Rasipuram – 637408
MUTHAYAMMAL ENGINEERING COLLEGE
(An Autonomous Institution)
(Approved by AICTE, New Delhi, Accredited by NAAC, NBA & Affiliated to Anna University),
Rasipuram - 637 408, Namakkal Dist., Tamil Nadu.
Clamping Circuit and Clipping Circuit

2. Clamping Circuit
The circuit which can set the positive or negative peak of the input AC signal at a
required level is what we call as a clamping circuit. This circuit quickly adds or
subtracts a DC element to the input AC signal. Other than the name clamping
circuit, Baseline Stabilizer or DC Reinserted or Level Shifter or D.C Restorer are
also frequently used.
 The requirement of clamper circuit is similar to in TV receivers; where the
signal moves through the capacitive coupling network, then the dc component
of these signal will get lost. This DC component (not exactly same as that of the
lost one) will get restored using this clamping circuit. This circuit will add the
DC element which will be positive or negative to the AC input signal. It pushes
the signal towards the positive or the negative side (shown below). Here; when
it shifts the signal to upward side or positive side, both negative peak and the
zero level will meet which is called positive clamper circuit.
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3. Contd..
 When it shifts the signal to the downside or negative side, both positive peak
and the zero level will meet which we refer as the negative clamper circuit.

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4. Contd..
 The minimum number of components of a clamping circuit is three – a capacitor,
a resistor and a diode. In some cases, DC supply is also needed to give an
additional shift. The nature of the waveform remains alike, but the difference is in
the shifted level. The peak to peak value of the waveform will never change.
The peak value and average value of the input waveform and the clamped output
will be different. The time constant of the circuit (RC) must have to be ten times
the time-period of the entering (input) AC voltage for better clamping action.
 Now, we can assume a negative clamper shown in figure 2. Throughout the
positive half cycle of input, the D diode will conduct, and the output voltage will
be same as barrier potential of the diode (V0). At that time, the capacitor will get
charged to (V – V0). Throughout the negative half cycle of input, the diode will
become negative biased, and it has no role on capacitor voltage. The capacitor
cannot discharge a lot because of the high value of R. Therefore output voltage
will be – (2V- V0). The peak to peak voltage will be 2V. The output waveform that
we get will be the original signal shifted in the downward direction.
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5. Contd..
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Next, we can assume a positive clamper shown in figure 3. The one and only
distinction from the previous circuit is that diode is in reverse polarity. So the output
will be the shifted original signal in the upward direction.

6. Contd..
 The explanation and working are same as above clamper circuit. Thus we can
conclude that we obtain the positive clamper if the diode in the circuit points
the upward direction and we get negative clamperwhen the diode points in the
downward direction.
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7. Contd..
Principle of Operation of Clamping Circuit
In general, the clamper circuit depends on a variation in the capacitor time constant
The time constant should be sufficient that the capacitor voltage does not discharge
considerably throughout the non-conducting diode period. One should select the
values of capacitance and resistance in such a way that the circuit keeps the time
constant high. For preventing quick the discharge of capacitor, the resistance value
should be high. All through the diode conducting period, the capacitor charging
should be very fast. For this, we select a small value of capacitance.
The C in the positive clamper charges quickly throughout the first negative phase of
AC input voltage. When Vin becomes +ve, the C serves as a voltage doubler and
when Vin is –ve, the C operates as a battery with voltage Vin. Thus, we can conclude
that the capacitor and input voltage act against each other. This results in zero net
voltage as seen by the load.
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8. Contd..
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Biased positive clamping circuit

9. Contd..
Biased negative clamping circuit
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10. Classification of Clipping Circuit
According to non linear devices used
- Diode Clippers.
- Transistor Clippers.
According to biasing
- Unbiased Clippers.
- Biased Clippers.
According to configuration used
- Series diode clippers.
- Shunt or Parallel diode clippers.
- A series combination of reference supply, resistor and diode.
- Multi-diode clippers comprises of a number of diodes, resistors and
reference voltage.
- Two emitter-coupled transistors functioning as an over driven difference
amplifier.
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11. Classification of Clipping Circuit
According to non linear devices used
- Diode Clippers.
- Transistor Clippers.
According to biasing
- Unbiased Clippers.
- Biased Clippers.
According to configuration used
- Series diode clippers.
- Shunt or Parallel diode clippers.
- A series combination of reference supply, resistor and diode.
- Multi-diode clippers comprises of a number of diodes, resistors and
reference voltage.
- Two emitter-coupled transistors functioning as an over driven difference
amplifier.
.
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12. Clipping Circuit
 It is in fact a wave shaping circuit, which can control the shape of the output
waveform by eliminating or clipping a part of applied wave. This is done
without distorting the other (remaining) part of waveform.
 The clipping circuit does not have energy storage elements (capacitors) but it
includes both linear (Resistors) and nonlinear elements (transistors or junction
diodes). This circuit is normally used for the selection in the transmission
purpose.
 In transmission, a portion of a signal wave form occupied below or above a
particular reference voltage level is selected. Other than the name – Clipping
circuits; Slicers, Clippers, Limiters or Amplitude selectors are also often used.
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13. Contd..
Diode Clippers
 At least two components – an ideal diode and resistor are employed for the
formation of these clippers. In some cases; for fixing the clipping level, a DC
battery is also used (Figure 1). When the circuit is forward biased, the ideal
diode used operates as a closed switch.
 When the circuit is reversed biased, the ideal diode used operates as an open
switch. Here; by altering the voltage of the battery and by exchanging the
position of the various elements, the input waveform can be clipped.
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14. Contd..
Positive clippers
It actually removes the positive half cycles of the input voltage. Here in positive
series clipper, when the input is positive then the diode is in reverse biased condition
(output is zero) and when the input is negative, then the diode is in forward biased
condition (figure 2)
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15. Contd..
In positive shunt clipper, when the input is negative, the whole input voltage appears
across the resistor RL or diode (if R<L). When R<L, this circuit will operates as
voltage divider and its output voltage is
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16. Contd..
When the diode is connected in reverse polarity in the circuits of positive series
clipper and positive shunt clipper, it becomes negative series clipper and negative
shunt clipper respectively (figures 4 and 5). These clippers can eliminate the entire
negative half cycle of input voltage.
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17. Contd..
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The clippers discussed above are considered as the circuits with ideal diode. But if
the barrier potential (V0) is considered (Si = 0.7 V and Ge = 0.3 V), the output
voltage of positive and negative clippers are shown below.

18. Contd..
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Biased Clippers
In some cases, we need to eliminate a tiny portion of positive or negative half cycles of
the input signal voltage. In that case we use biased clippers.
While during the negative half cycle of input signal in biased negative clipper circuit, it
removes the input signal voltage when it is greater than the battery voltage. When the
battery and diode is reversed, the clipping can be changed to biased positive clipper
(Figure 7).

19. Contd..
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20. Contd..
Combination Clipper
 For removing a portion of both positive and negative half cycle of input signal,
we use this combination clipper (figure below).
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21. Contd..
Zener Diode as a Peak Clipper
Zener diodes can be employed for removing (clipping off) the portion of input
waveform in the wave shaping circuit (see figure below).
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22. Contd..
Application of Clipper
 TV Transmitters and Receivers.
 Noise Limiters.
 Protection of different circuits.
 Different wave generation.
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23. Thank You
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