Varactor diode, is a diode that has a variable capacitance which is a function of the voltage that is impressed on its terminals. Varactor diodes are operated reverse-biased, and therefore no current flows. However, since the thickness of the depletion zone varies with the applied bias voltage, the capacitance of the diode can be made to vary. Usually, the capacitance is inversely proportional to the depletion region thickness and the depletion region thickness is proportional to the square root of the applied voltage. Therefore, the capacitance is inversely proportional to the square root of the voltage applied to the diode.

  • It is also known as tuning diode or Variable Capacitance diode or Varicap diode or Variable Reactance diode.

In this too they are several types if varactor diodes or tuning diodes :

There are several different kinds of tuning / varactor diodes. At Future Electronics we stock many of the most common types categorized by power dissipation, nominal diode capacitance, minimum diode capacitance ratio, minimum breakdown voltage, packaging type and diode cap tolerance. The parametric filters on our website can help refine your search results depending on the required specifications.

The most common sizes for nominal diode capacitance are 22 pF and 33 pF. We also carry varactor diodes with nominal diode capacitance up to 100 pF. Minimum breakdown voltage can be up to 30 V, with the most common size being 25 V.

This diodes are from future electronics :

Future Electronics has a complete selection of varactor diodes from several manufacturers that can be used as a variable capacitance diode for any circuit requiring a varactor diode. Simply choose from the tuning / varactor diode technical attributes below and your search results will quickly be narrowed in order to match your specific varactor diode application needs.

If you have a preferred brand, we deal with ON Semiconductor and Zetex. You can easily refine your varactor diode product search results by clicking your preferred varactor diode brand below from our list of manufacturers.

Applications or uses of them :

Varactor diodes are often used in RF design. They provide a way of varying the capacitance within a circuit by applying a control voltage. Due to this capability, tuning / varactor diodes are widely used in the RF industry. They can be found in voltage controlled oscillators such as in a phase locked loop and are used in almost all radio, cellular and wireless receivers. They can also be found in RF filters for tuning purposes, parametric amplifiers, parametric oscillators and frequency synthesizers.

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