Q5. a) What is a filter circuit? b) Describe the action of the following filter circuits with the aid of a diagram: i. Capacitor filter ii. Choke input filter c) Explain how a Zener diode maintains constant voltage across a load.

Discuss the principle of operation of a varactor diode and its applications in frequency - modulated circuits.

Suppose we have a silicon diode operating with a bias current of 5 mA at a temperature of 300 K. The diode current is given by the Shockley equation with n=2 .Draw the small-signal equivalent circuit for the diode including numerical values for the components.

Design a 15 V Zener regulator for the following conditions: 1) The load current IL ranges from 200 mA to 300 mA.2) The source voltage ranges from 21 V to 25 V. Based on your design results,a) Draw the Zener regulator circuit.b) Calculate the power ratings for both Zener diode and resistor Ri