What part of the varactor produces the capacitance?

The capacitance of the varactor diode increases with the increase of n and the p-type region and decreases with the increases of the depletion region. The increase in capacitance means the more charges are stored in the diode.

What is a varicap diode used for?

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 will happened to the capacitance of the varactor diode If the applied voltage is greater?

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.

Which capacitance plays a major role in varactor diode?

In time, varicap diodes were developed which exhibited large capacitance ranges, 100–500 pF, with relatively small changes in reverse bias: 0–5 V or 0–12 V.

What will happen to the depletion region of a varicap If you decrease the reverse bias voltage?

If the reverse bias voltage is increased, the width of depletion region further increases and the capacitance further decreases. On the other hand, if the reverse bias voltage is reduced, the width of depletion region decreases and the capacitance increases.

Is a diode a variable capacitor?

The variable-capacitance diode is a product that makes use of the capacity characteristics of the depletion layer. Therefore, as the reverse voltage applied increases, the capacitance decreases. …

Why is a varicap diode operated with a reverse bias?

The varactor diode should always be operated in reverse bias. Because in reverse bias, the electric current does not flow. When a forward bias voltage is applied, the electric current flows through the diode. As a result, the depletion region becomes negligible.

Why a PN junction has capacitance?

The depletion region of the p-n junction diode has high resistance. Hence, the depletion region acts like the dielectric or insulating material. Therefore, charge is stored at the depletion region in the form of electric field. The ability of a material to store electric charge is called capacitance.

How does capacitance vary with applied voltage?

Capacitance is a fixed value of manufacturing, capacitance does not vary with applied voltage.

What is the capacitance range of a varicap diode?

Early varicap diodes usually required a reverse voltage range of 0–33 V to obtain their full capacitance ranges, which were still quite small, approximately 1–10 pF. These types were – and still are – extensively used in television tuners, whose high carrier frequencies require only small changes in capacitance.

What is Varicap diode used for?

Varicap. In electronics, a varicap diode, varactor diode, variable capacitance diode, variable reactance diode or tuning diode is a type of diode designed to exploit the voltage-dependent capacitance of a reverse-biased p–n junction.

What is the difference between hyperabrupt junction profile capacitance and varicap?

For hyperabrupt junction profile capacitance change is more non-linear, but hyperabrupt varicaps have larger capacitance variation and can work with lower voltages. All diodes exhibit this variable junction capacitance, but varactors are manufactured to exploit the effect and increase the capacitance variation.

How much voltage should be maintained across a varicap?

When designing tuning circuits with varicaps it is usually good practice to maintain the AC component of voltage across the varicap at a minimal level, usually less than 100 mV peak to peak, to prevent changing the diode capacitance too much, which would distort the signal and add harmonics.