Embodiments of the present invention provide a power amplifier, a transceiver, and a base station. The power amplifier includes: a signal control unit, configured to generate a mode control signal and an auxiliary power amplifier control signal; a signal processing unit, configured to separately process an envelope signal and a radio-frequency signal; an envelope modulator, configured to output a fixed voltage or output an amplified envelope signal under the control of the mode control signal; a primary power amplifier, configured to perform amplification processing on the received radio-frequency signal that is input from the signal processing unit; and at least one auxiliary power amplifier, configured to operate or be disabled under the control of the auxiliary power amplifier control signal, and when in an operating state, perform amplification processing on the received radio-frequency signal that is input from the signal processing unit.