What is the principal characteristic of a varactor diode?
The V-I characteristics of the diode are non-linear and it permits the flow of current in only one direction In forward bias mode, the diode allows the flow of current and offers very low resistance. Likewise, in the reverse bias mode, the diode blocks the current flow and offers very high resistance.
Under what bias condition is a varactor operated?
reverse bias condition
Varactor diodes are normally operated in the reverse bias condition. When the reverse bias increases, the width of the depletion region also increases resulting in less capacitance. This means when reverse bias decreases, a corresponding increase in capacitance can be seen.
When reverse biased a varactor diode acts a?
variable capacitor
Fig : The reverse-biased varactor diode acts as a variable capacitor. As the reverse-bias voltage increases, the depletion region widens, effectively increasing the plate separation, thus decreasing the capacitance. When the reverse-bias voltage decreases, the depletion region narrows, thus increasing the capacitance.
What is the working principle of varactor diode?
Definition: Varactor diode is the one which works on the principle of variation in capacitance by changing the width of the depletion region of P-N junction. The P-N Junction diode creates capacitor effect. The capacitance is controlled by applied voltage. It works on reverse biased mode.
What is varactor diode and where it is used?
Varactor diodes are used in electronic tuning systems to eliminate the need for moving parts. Varactor [also called varicap, variable reactance diode, or tuning diode] diodes are the semiconductor, voltage-dependent, variable capacitors.
What is varactor diode and its application?
Varactor or varicap diodes are used mainly in radio frequency or RF circuits to provide voltage controlled variable capacitance. These electronic componenta can be used in a whole variety of ways where a capacitance level needs to be controlled by a voltage.
What is a varactor diode symbol of varactor diode?
Symbol of Varactor Diode The symbol of the varactor diode is similar to that of the PN-junction diode. The diode has two terminals namely anode and cathode. The one end of a symbol consists the diode, and their other end has two parallel lines that represent the conductive plates of the capacitor.
What is varactor diode why is it termed as varactor diode?
Ans: The word Varactor indicates varying reactance. As these diodes are mainly used because of their peculiar property of varying capacitance by regulating the reverse-biased voltage, they are termed as Varactor diodes.
When the reverse bias potential is increased across a varactor diode?
So if we need to increase the capacitance of a varactor diode, the reverse bias voltage should be decreased. It causes the width of the depletion layer to decrease, resulting in higher capacitance. Similarly, increasing the reverse bias voltage should decrease the capacitance.
What is varactor modulator?
Varactor diode modulator is the direct method of FM generation wherein the carrier frequency is directly varied by the modulating signal. Varactor diodes are used along with reactance modulator to provide automatic frequency correction for an FM transmitter. The varactor diode modulator circuit is shown in Fig5.