A power amplifier gain switching circuit includes: a gain controller configured to receive an external input signal, output a first input signal, receive an external drive signal, and output a control signal based on the drive signal; an amplifier including: a bias input terminal configured to receive an external bias voltage; a signal input terminal configured to receive the first input signal; a control terminal configured to receive the control signal; and an output terminal configured to output an output signal with a gain; wherein the amplifier is configured to switch a gain factor of the output signal based on the control signal.