What does varactor mean?
A varactor is an electronic component whose capacitance changes with the voltage applied to it. Also called a variable-capacitance diode, it is used particularly in radio-frequency and microwave circuits to tune an oscillator, alter a filter, or provide controllable reactance. The device does not itself generate a signal; instead, it supplies an adjustable electrical characteristic that helps determine the operating frequency of the surrounding circuit. In radio receivers and transmitters, a varactor may be varied to select or tune a desired station or frequency. Because voltage can control capacitance, varactors make compact electronic tuning and frequency control possible. The term belongs to electronics and telecommunications rather than ordinary vocabulary, but it remains useful for understanding voltage-controlled tuning in modern radio and microwave equipment. Its combination of “variable” and “reactor” also makes it memorable: the component reacts to an applied voltage by changing the electrical behavior of a circuit.
nounA voltage-dependent semiconductor device used as a variable capacitor, especially in radio-frequency and microwave circuits to tune oscillators or adjust circuit frequency.
- A voltage-dependent, variable-capacitance semiconductor device used to tune or adjust the frequency of radio-frequency and microwave circuits.
"The technician adjusted the varactor to bring the oscillator onto the desired frequency."
"The technician adjusted the varactor to bring the oscillator onto the desired frequency."
"A varactor diode provided voltage-controlled tuning in the radio receiver."
The plural is used when referring to multiple voltage-dependent variable-capacitance devices.
"Several varactors were mounted near the tuning controls."
A varactor turns a change in voltage into a change in capacitance, making electronic tuning possible.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of varactor
Varactor is a technical coinage combining variable with the “-actor” element familiar from reactor. Variable comes through Latin variabilis from varius, meaning “varied” or “various,” while reactor is formed from react, reflecting the idea of acting back.
How varactor is actually used
Chiefly used in electronics and telecommunications engineering. In technical usage, it normally refers specifically to a semiconductor junction device rather than a mechanically adjustable variable capacitor.
Easily confused with varactor
A reactor converts or processes energy through a chemical or nuclear reaction, whereas a varactor is an electronic device whose capacitance changes with applied voltage.