Patent ID: 6657509
Filing Date: 2003-12-02
Classification: H03B

Abstract:
An electronic circuit with at least one differentially controlled variable capacitance, comprising:a first differentially controlled variable capacitance has a first differential input and is connected to a first common node that is biased to a potential; a second differentially controlled variable capacitance has the first differential input and is connected to a second common node that is biased to a potential; a third differentially controlled variable capacitance has a second differential input and is connected to the first common node; a fourth differentially controlled variable capacitance has the second differential input and is connected to the second common node; a first differential control signal that is connected to the first differential input such that the first differential control signal changes a first capacitance value associated with the first differentially controlled variable capacitance and changes a second capacitance value associated with the second differentially controlled variable capacitance, wherein common mode noise at the first and second common nodes is minimized; and an oscillator circuit that oscillates at an oscillation frequency, wherein the first, seconds, third and fourth differentially controlled variable capacitances are arranged to tune the oscillation frequency, wherein the first and second differentially controlled variable capacitances provide fine adjustment of the oscillation frequency and the third and fourth differentially controlled variable capacitances provide coarse adjustment of the oscillation frequency.