Patent ID: 6847095

Claim:
A variable reactor (varactor) with engineered capacitance-voltage (C-V) characteristics, comprising: a first node; a second node; at least one first varactor element comprising a source, a drain, and a p-type doped gate, the at least one first varactor element being associated with a first C-V curve; at least one second varactor element comprising a source, a drain, and an n-type doped gate, the at least one second varactor element being associated with a second C-V curve; at least one third varactor element comprising a source, a drain, and an intermediately doped gate, the intermediately doped gate having doping characteristics intermediate to doping characteristics of the p-type and n-type gates, the at least one third varactor element being associated with a third C-V curve; and one or more wells in a substrate region underlying the first, second, and third varactor elements; the first, second, and third varactor elements being coupled in parallel between the first and second nodes, the varactor exhibiting a composite C-V curve: reflecting a combination of the first, second, and third C-V curves when a voltage is applied between the first and second nodes; exhibiting an increased tuning range relative to the first C-V curve associated with the first varactor element; and exhibiting increased linearity relative to the second C-V curve associated with the second varactor element; and the varactor being associated with a total capacitance (C total ), where C total =a*n+b*p+c*i, where a, b, and c each comprise a weight factor for engineering a predetermined composite C-V curve and where n, p, and i comprise unit capacitors for the n-type doped gate, the p-type doped gate, and the intermediately doped gate, respectively.