(a) Draw circuit diagram and explain the working of a zener diode as a dc voltage regulator with the help of its I-V characteristic.
(b) What is the purpose of heavy doping of p- and n-sides of a zener diode ?




 

a) If the input voltage increases, the current through Rs and Zener diode also increases. This increases the voltage drop across Rs without any changes in the voltage across the Zener diode. This is because in the breakdown region, Zener voltage remains constant even though the current through that Zener diode changes.

(b) To decrease the width of depletion region which increases electric field at the junction.