Patent ID: 7660563

Claim:
A mixer, comprising: a first differential transistor pair coupled to a first node; a second differential transistor pair cross-coupled to the first differential transistor pair and coupled to a second node; a third differential transistor pair coupled to the first and second nodes; a feedback circuit coupled to the first node and the second node, and configured to generate a calibration signal based on a measured signal offset between the first and second nodes during both a calibration mode and an operating mode; a modulation input circuit coupled to the third differential transistor pair, and responsive to the calibration signal, wherein the modulation input circuit is configured to receive an input signal having substantially all desired frequency components above a first cut-off frequency; and a control loop formed by the feedback circuit and the modulation input circuit, the control loop having a bandwidth from DC to a second cut-off frequency that is less than the first cut-off frequency.