Patent ID: 6737851
Filing Date: 2004-05-18
Classification: H03H,H03J

Abstract:
An electrical circuit comprising:a filter including at least a first variable capacitor and a second variable capacitor and at least a first and second resistor; and a calibration circuit comprising: a current source; a transistor communicating in series with said current source, the transistor including a gate; an integrator communicating with the gate of the transistor; a third capacitor; a first switch communicating between the integrator and the third capacitor; a fourth variable capacitor; a second switch communicating between the third capacitor and the fourth variable capacitor, the second switch having a closed position, wherein the third capacitor and the fourth variable capacitor are in a parallel arrangement when the second switch is in the closed position; a third switch in parallel with the fourth variable capacitor; a first current mirror communicating with each of the third switch, the fourth variable capacitor and the second switch, wherein the first current mirror mirrors the current source; a second current mirror which proportionally mirrors the current source; a third resistive element in series with the second current mirror; and a digital loop communicating with each of the first, second, and fourth variable capacitors.