Power amplifier system with gain expansion compensation

A method of operating a power amplifier system comprising an output stage, a driver stage configured to have a controllable soft compression characteristic, and a controller configured to generate and send a soft compression control signal to the driver stage, the method comprising:

• determining by way of the controller that the output stage is entering early gain expansion;
• generating the soft compression control signal upon determination of early gain expansion in the output stage;
• and
• sending the soft compression control signal to select by-pass capacitance of selectable by-pass capacitors associated with the driver stage to adjust the soft compression characteristic of the driver stage and thereby substantially reduce the gain expansion of the output stage.

A wireless communication device comprising:

• a baseband processor;
• transmit circuitry configured to receive encoded data from the baseband processor and to modulate a carrier signal with the encoded data, wherein the transmit circuitry comprises:
• an output stage having a radio frequency (RF) output and power amplifier input;
• a driver stage having a driver input coupled to the RF input, a control input, and a driver output coupled to the power amplifier input, wherein the driver stage is configured to have a controllable by-pass capacitance in response to control signals;
• and
• a controller having control outputs coupled to the control input of the driver stage, wherein the controller is configured to generate the control signals that adjust the by-pass capacitance associated with selectable by-pass capacitors coupled to gates of transistors comprising the driver stage to substantially neutralize a gain expansion characteristic of the output stage.