# Clipper & Clamper

A circuit which cutoff voltage above or below are both at specified level is called clipper. A clipper which removes a portion of positive half cycle of the input signal is called positive clipper. A clipper circuit that removes the negative half cycle is called negative clipper. Figure (a) Positive Clipper (b) Negative Clipper

Figure (a) shows the circuit of a positive clipper. It consists of a diode D and a resistor R with outputs taken across the resistor. During positive half cycle of the input voltage, the terminal A is positive with respect to B. This reverse biases the diode and it acts as an open switch. Therefore all the applied voltage drops across the diode and none across the resistor. As a result, there is no output voltage during the positive half cycle of the input voltage.

During the negative half cycle of the input voltage, the terminal B is positive with respect to A. Therefore it forward biases the diode and it acts as a closed switch. Thus, there is no voltage drop across diode.

During negative half cycle of the input voltage. All the input voltage drops across the resistor as shown in the output waveform.

Figure (b) shows the waveform of the input voltage. During the positive half cycle of the voltage, the terminal A is positive with respect to the terminal B. Therefore the diode is forward biased; as a result all the input voltage appears across the resistor.

During negative half cycle of the input voltage, the terminal B is positive with respect to the terminal A. Therefore the diode is reverse biased and hence there is no voltage drop across the resistor during negative half cycle.

## Biased Clipper Circuit

If bias voltage is placed in series with diode then the circuit is called biased clipper or limiter circuit. This bias determines the point where the diode begins to conduct and duration of conduction. With bias, clipping can be done to any percent of the input signal ranging from 1% to 99%.

## Single End Clipper Figure (c): Single End Clipper / Shunt Positive Clipper

Figure (c) shows a single end positive clipper. Notice that the positive terminal of the battery connected to the diodes cathode therefore diode conducts when input voltage reaches at the level of 4.7 volt (VBias + 0.7). And when diode is conducting there will be no current in RL and no voltage will drop across RL. So that all the input voltage above this level will be clipped off at the output.

If the bias voltage is varied up or down the clipping level changes correspondingly.

## Double Diode Clipper

A circuit that can be used to limit the peaks of both half cycles of an A.C. input signal is called double end clipper.

A circuit diagram for this circuit is shown in Figure (d)

Notice that this circuit contains a shunt positive clipper with positive bias and shunt negative clipper with negative bias.

When the biased voltage reaches +8.7V diode D1 conducts and above that volt level no current flow through RL. Hence limiting the waveform to 8.7V. Diode D2 does not conduct until the voltage reaches -6.7V and negative voltage bellows -6.7V are clipped off. The resulting output waveform is shown at the output of the circuit.

## Clamping

A circuit that clamps either the positive or negative peak of a signal at a desired D.C level is known as a clamping. A clamping adds a D.C components to the signal and does not change the shape or amplitude of the input signal.

## Diode Clampers

### Positive Clamper

Diode clamping circuit simply consists of a diode D and capacitor C as shown in below Figure.