A transceiver comprises an amplifying circuit for amplifying an input signal to produce an output signal. A power supply is operable for varying the level of power supplied to the amplifying circuit in response to variation of an input signal envelope directed to the power supply. A processing circuit is operable for digitally detecting the input signal envelope to provide variation of the power supply level. The processing circuit is further operable for digitally delaying the digital input signal envelope to time align the power supply level with the input signal.