Q What is a clipper? Describe the operation of a biased clipper and combination clipper.

The circuit with which the waveform is shaped by removing (or clipping) a portion of the input signal without distorting the remaining part of the alternating waveform is called a clipper. Clipping circuits are also referred to as voltage (or current) limiters, amplitude selectors or slicers. These circuits find extensive use in radars, digital computers, radio and television receivers etc.

Biased clipper: In some applications, it is required to remove a small portion of positive or negative half cycle of the signal voltage and hence the biased clipper is used. The name bias is designated because the adjustment of the clipping level is achieved by adding a biasing voltage in series with the diode or resistor. The different types of biased clippers are:

· Biased positive clipper

· Biased positive clipper with reverse polarity of the batteryVR.

· Biased negative clipper

· Biased negative clipper with reverse polarity of the batteryVR.

Combination clipper: This is the combination of a biased positive clipper and a biased negative clipper. When the input signal voltage V ³ +V , diode D  conducts and acts as a closed switch, while D2 is reverse biased and acts as a open switch. Hence, the output voltage cannot exceed the voltage level of +VR₂ during the positive half cycle. Similarly the output voltage Vo cannot go below the voltage level of -VR2 during the negative half cycle.