Patent ID: 6674116
Filing Date: 2004-01-06
Classification: H01L

Abstract:
A varactor comprising:a metal-oxide-semiconductor (MOS) gated diode having a gate, a source, and a substrate; wherein the gate also comprises a gate resistor between an upper-gate contact and a lower-gate contact; an upper voltage applied to the upper-gate contact; a lower voltage applied to the lower-gate contact; wherein the upper voltage and the lower voltage are not equal, causing a gate current to flow through the gate resistor and producing a voltage gradient along the gate wherein gate-to-source voltages vary along the voltage gradient; a first capacitor terminal, connected to the source and having a source voltage, the source voltage sufficient to cause formation of an inversion layer under a first portion of the gate but insufficient to cause formation of an inversion layer under all of the gate; wherein the inversion layer is electrically coupled to the source; a second capacitor terminal connected to a substrate under the inversion layer; and a drain alongside the gate, and coupled to the first capacitor terminal; wherein the drain and source and both biased to the source voltage, whereby capacitance between the first and second capacitor terminals is varied by enlarging or reducing an area of the first portion.