What is varactor diode and where it is used?

A varactor diode is a p-n-junction diode, in which internal capacitance can be altered as a result of the application of reverse bias voltage. The varactor or varicap diodes are used to store charges. Diodes are the electronic components used to conduct the flow of electrons in one direction.

Who invented varactor diode?

Erik Kollberg
The device was invented by Erik Kollberg together with Anders Rydberg in 1989 at Chalmers University of Technology.

What are the specifications of varactor diode?

The actual capacitance range for a varactor diode depends upon a number of factors: the area of the junction; the width of the depletion region for a given voltage, etc. It is found that the thickness of the depletion region in the varactor diode is proportional to the square root of the reverse voltage across it.

Which of the following property exists in varactor diode?

The varactor diode is manufactured in such as way that it shows better transition capacitance property than the ordinary diodes.

What is the use of a varactor diode in radio receiver?

Varactor diodes are mainly used in Voltage Controlled Oscillators (VCOs) and RF Filters for tuning the receiver to the incoming signal or different stations.

What is varactor diode modulator?

Varactor diode modulator is the direct method of FM generation wherein the carrier frequency is directly varied by the modulating signal. A varactor diode is a semiconductor diode whose junction capacitance varies linearly with applied voltage when the diode is reverse biased.

How does varactor modulator work?

Why is varactor diode often made by epitaxial growth technique?

Varactor diode manufacturers typically use an epitaxial structure to minimise this resistance. When designing the circuit, the Q of the circuit can be maximised by minimising the capacitance. These are the main varactor specifications that need to be considered outside the basic diode specifications.

Which of following property exists in varactor diode?

Varactor Diode Varactor diode is a type of diode whose internal capacitance varies with respect to the reverse voltage. It always works in reverse bias condition and is a voltage-dependent semiconductor device. Varactor diode is known by several names as Varicap, Voltcap, Voltage variable capacitance, or Tunning diode.

Where is varactor diode used in communication circuits?

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 used for?

A varactor diode, also called varicap, VVC (voltage-variable capacitance, or tuning diode, is a type of semiconductor diode which features a variable voltage-dependent capacitance on its p-n junction when the device is reversed biased.

How to design circuits that use the properties of a diode?

For designing circuits that use the properties of a varactor diode, we first need to break down its electrical properties and visualize an equivalent circuit with basic components like resistors, capacitors and inductors. The below image shows such approximate equivalent circuit of a varactor diode when operated under reverse bias condition.

What is the equivalent circuit of a varactor diode under reverse bias condition?

The below image shows such approximate equivalent circuit of a varactor diode when operated under reverse bias condition. RR is the reverse bias resistance and RG is the geometric resistance of the varactor diode. CJ is the junction capacitance which is dependent on the reverse bias voltage.

How to study varicap diode datasheet?

Complete Datasheet of a typical varicap diode can be studied from the following figure: The ratio of C3/C25 in the above figure, demonstrates the ratio of the capacitance level when the diode is applied with a reverse bias potential between 3 to 25 V.