Patent ID: 6794707
Filing Date: 2004-09-21
Classification: H01L,H03B

Abstract:
A variable capacitor comprising:first terminal means for applying a variable capacitance to another circuit, the first terminal means having a source voltage; substrate connection means for connecting to a substrate to bias the substrate; composite gate means, having a plurality of gate segments formed over the substrate, for inducing formation of a conducting channel in the substrate under a gate segment when a gate-segment voltage of the gate segment exceeds the source voltage by a threshold voltage, but for not forming the conducting channel when the gate-segment voltage of the gate segment does not exceed the source voltage by the threshold voltage; source means, formed in the substrate but having an opposite polarity to the substrate, for connecting conducting channels under the gate segments to the first terminal means and for biasing the conducting channels under the substrate to the source voltage of the first terminal means; variable voltage means for generating a first voltage that can be varied to adjust a capacitance value of the variable capacitance; and multi-voltage means, coupled between the variable voltage means and a second voltage, for generating a plurality of voltages between the first and second voltages; wherein the plurality of voltages are each applied to a different one of the gate segments whereby the gate segments are biased to a plurality of differing gate-segment biases between the first and second voltages, whereby the capacitance value at the first terminal means is increased by adjusting the first voltage, causing additional gate segments to form conducting channels that increase capacitance.