Varactor

Part of speech: noun

Definitions

1. A specific type of semiconductor component that alters its capacitance depending on the voltage applied across it serves primarily in radio frequency tuning circuits
2. This device functions as a variable capacitor, modulating its capacitance in response to reverse voltage, typically utilized in electronic tuning and signal filtering applications
3. A semiconductor device that changes its capacitance with applied voltage, mainly found in radio applications like tuning and filtering signals

Etymology: Varactor is a blend of "variable" and "reactor," and the blend tells you what the device does. A reactor in electrical engineering is a component that opposes changes in current, and the "variable" part marks that its reactance can be adjusted. In practice, the varactor is a semiconductor diode whose capacitance shrinks as the reverse voltage applied across it grows. That voltage-controlled capacitance lets circuits retune themselves electronically rather than through a mechanical dial. The word thus packs two ideas into one compact coinage: a variable element and a reactive one. Engineers used the blend to name a component that behaves like a tunable capacitor, which is why it turns up so often in radio tuning and filtering circuits, where a single voltage can shift the frequency a circuit responds to.