👉 A varactor is a type of semiconductor device that consists of a thin, variable resistance region. It is used in electronic circuits to control the current flowing through a circuit, similar to how a resistor can be adjusted to change the amount of current flowing through it. The concept of a varactor was first introduced by J. A. von Kármán in 1925 and has since been widely applied in various fields such as radio frequency (RF) circuits, optical amplifiers,
