Variable Capacitance Diode - Characteristic, Symbol, Definition. Variable Capacitance Diode (Varicap Diode, also called Varactor Diode) – a special type of semiconductor diode. It is designed to exploit the changes in voltage-dependent capacitance of a reverse-biased “p-n junction”, therefore its ability to use junction barrier capacity has been improved. In other words, Varicap can be described as a voltage-controlled capacitor. Varicap Diodes are mostly manufactured from Silicon (Si) and Gallium Arsenide (GaAs). With its manufacture it is strived to achieve the highest value of voltage sensitivity (re-tuning diode factor).
Its capacitance can change in a narrow range, usually from about 6 pF (picofarads) to 20 pF with the voltage change from 2 to 20 V. The main parameters describing the varicap diode are its two limiting capacities: Ctmin – minimum capacity and Ctmax – maximum capacity. As mentioned above, these parameters are dependent on voltage. Variable Capacitance Diode detailed description Component division Limiting properties Applications.