Power amplifier using multi-path common-mode feedback loop

A power amplifier stage comprising:

• an input;
• an output;
• a common-mode supply input;
• a first n-type field effect transistor (FET) (NFET) comprising a first gate, the first NFET coupled to the input and the output;
• a first p-type FET (PFET) comprising a second gate, the first PFET coupled to the input and the output;
• a bias circuit coupled to the first gate and coupled to the second gate, the bias circuit configured to bias dynamically the first gate and the second gate with respective bias signals;
• a bias feedback loop coupled to the output and the bias circuit, the bias feedback loop comprising a voltage sensor configured to sense voltage at the output, wherein the respective bias signals are based on the sensed voltage;
• and
• a common-mode supply feedback loop comprising a current sensor configured to sense current for the first PFET and adjust a signal from the common-mode supply input based on the sensed current.

A power amplifier stage comprising:

• an input;
• an output;
• a first varactor and a second varactor coupled in parallel to the output;
• a first n-type field effect transistor (FET) (NFET) comprising a first gate, the first NFET coupled to the input and the output;
• a first p-type FET (PFET) comprising a second gate, the first PFET coupled to the input and the output;
• a bias circuit coupled to the first gate and coupled to the second gate, the bias circuit configured to bias dynamically the first gate and the second gate with respective bias signals;
• and
• a feedback loop coupled to the output and the bias circuit, the feedback loop comprising a voltage sensor configured to sense voltage at the output, wherein the respective bias signals are based on the sensed voltage.