Abstract: Circuits, methods, and systems are provided for opening a primary feedback loop in a transmitter. An auxiliary feedback loop can be closed when the primary feedback loop is opened, and a controller can match a gain of the primary feedback loop to another gain in the transmitter.

Abstract: A transconductance cell is disclosed that includes a first transistor and a second transistor. A regulator regulates an average voltage in response to a reference voltage, where the average voltage corresponds to the average of a voltage at a bias terminal of the first transistor and a voltage at a bias terminal of the second transistor. A mixer including the transconductance cell is also disclosed. In the mixer, the transconductance cell receives a differential input voltage and produces a differential output current. The mixer also includes one or more switches that multiply the differential output current with an oscillator signal. A method is disclosed that includes measuring an average voltage of a voltage at a bias terminal of a first transistor and a voltage at a bias terminal of a second transistor and regulating the average voltage responsive to the measured average voltage and a reference voltage.

Abstract: A circuit is provided that includes a Cartesian feedback loop. The Cartesian feedback loop includes one or more operational amplifiers. At least one of the operational amplifiers includes two or more cascaded amplifier stages and one or more bypass amplifier stages. The bypass amplifier stages are connected in parallel with the cascaded amplifier stages.