Mixer circuits and methods with matched bias currents

A method of reducing offset in a mixer circuit, the method comprising:

• sensing a bias current through a first transistor to generate a feedback signal;
• comparing the feedback signal to a reference voltage, and in accordance therewith, generating a bias control signal;
• and
• adjusting the bias of an amplifier coupled to at least one input of the mixer circuit to reduce the offset of the mixer circuit and an input signal to the mixer circuit.

A mixer circuit comprising:

• first and second transistors coupled to receive a first differential input signal;
• a third transistor coupled to provide bias current to the first transistor;
• a first sense circuit coupled to sense current through the third transistor;
• a first comparison circuit coupled to the first sense circuit and to a reference voltage, the first comparison circuit generating a bias control signal;
• and
• a first amplifier coupled to an input signal and providing the input signal to a gate of the third transistor,
• wherein the first amplifier receives the bias control signal on a bias control input and changes the level of offset of the input signal at the gate of the third transistor.