How does a varicap diode work?
A varactor diode is designed to store electric charge not to conduct electric current. So varactor diode should always be operated in reverse bias. When a reverse bias voltage is applied, the electrons from n-region and holes from p-region moves away from the junction.
What is varactor diode characteristics?
The characteristics of Varactor diode have the following: These diodes significantly generate less noise compared to other diodes. The cost of these diodes is available at lower and more reliable also. These diodes are very small in size and very lightweight. There is no use when it is operated in forwarding bias.
What will happen to the depletion region of a varicap if you use forward bias voltage?
When a forward bias voltage is applied, the electric current flows, as a result, the depletion region becomes negligible, which is undesirable. The junction capacitance of a p-n junction diode is inversely proportional to the width of the depletion layer.
When bias applied to a varicap diode in increased capacitance?
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 tunneling phenomenon in a diode?
As the width of the depletion layer reduces, charge carriers can easily cross the junction. Charge carriers do not need any form of kinetic energy to move across the junction. Instead, carriers punch through the junction. This effect is called Tunneling and hence the diode is called Tunnel Diode.
Which diode can be used in tuning circuit?
A varactor diode is a simple variable capacitor that allows oscillator circuits and other circuits to be easily tuned by applying a voltage. These diodes have a similar structure as a p-n diode; the structure of a varactor diode is rather simple and illustrates its power as a component with nonlinear reactance.
How varicap is used as variable capacitor?
Generally the use of a varicap diode in a circuit requires connecting it to a tuned circuit, usually in parallel with any existing capacitance or inductance. A DC voltage is applied as reverse bias across the varicap to alter its capacitance. The DC bias voltage must be blocked from entering the tuned circuit.
What is difference between ordinary diode and varactor diode?
In a normal PN junction diode, doping impurities are usually dispersed equally throughout the material. Varactor diode doped with a very small quantity of impurities near the junction and impurity concentration increases moving away from the junction.
Why varactor diode is also called varicap explain?
A Varactor diode is known as a p-n-junction diode, where the internal capacitance can be altered as a result of the application of reverse bias voltage. Varactor diodes work in the reverse bias condition. They are also known as Varicap diodes or volt Cap diodes indicating varying capacitance.
Which of the diode vary the capacitance on changing the reverse bias?
A varactor diode is a diodes is reverse bias capacitance can be varied by changing the reverese bias voltage.
How does capacitance vary with applied voltage?
Capacitance is a fixed value of manufacturing, capacitance does not vary with applied voltage.
What are the characteristics of tunnel diode?
The I-V characteristics of a tunnel diode exhibit
- current-controlled negative resistance.
- voltage-controlled negative resistance.
- temperature-controlled positive resistance.
- current-controlled positive resistance.
What is a variable capacitor diode?
The variable-capacitance diode is a product that makes use of the capacity characteristics of the depletion layer. The depletion layer occurs in the pn junction of the diode when the voltage is applied in the reverse direction, and the thickness varies in proportion to the reverse voltage.
How does varactor diode help produce FM?
Varactor Diode Modulator Working And FM Generation – TESCKT. diode. By adharsh May 30, 2021. May 30, 2021. The modulation process is an important part of the communication system, superimpose high frequency with our main signal is the process that happened at the modulator device. The modulator has applications at every communication system, if
How does a varactor diode work?
– Voltage controlled oscillators, VCOs: Voltage controlled oscillators are used in many different RF designs. One major area is for the oscillator within phased locked loops. – RF filters: Using varactor diodes makes it possible to tune filters. – Frequency & phase modulators: Varactor diodes can be used in frequency and phase modulators.
What are the types of diode?
P-N Junction Diode. This is the basic diode formed with the interaction of p-type and n-type materials.