Varactor diode in radio receiver

In radio receivers, varactor diodes are used for

Options:

a) Tuning
b) Demodulation
c) Mixing
d) None of the above

Correct Answer: a.) Tuning

Explanation:

Varactor diodes are variable capacitance diodes that have a variable capacitance which is a function of the voltage applied at the input of its terminals. With the applied bias voltage, the capacitance of the diode can be varied. So the diodes are used for tuning at the receivers. Varactor diodes operate when they are reverse-biased. Varactor diodes are often used in RF circuits. They are used in voltage controlled oscillators in a phase locked loop. Practical applications of varactor diodes are radio receivers, cellular receivers and wireless receivers.