Q. What is the need of the resistance used in a clipper?
Resistor is used in a clipper to limit the current through the diode. To avoid the damage due to excessive current through it. Usually in a clipper, diode operates in two modes, either 'ON' or 'OFF'. When the diode is ON, the series resistance must be much higher than forward resistance of the diode because almost all input voltage will drop across the input resistor. But when the diode is OFF, series resistance must be very smaller than the reverse resistance of the diode. The value of resistance used in a clipper is the mean of forward resistance and reverse resistance. It is given by
Resistance, R = √(Rf.Rr)
Where Rf - is the forward resistance of the diode and
Rr - is the reverse resistance of the diode.