A radio frequency power amplifier system, comprising: an RF power amplifier; a digital-to-RF modulator to generate an RF input signal for the RF power amplifier based on input information indicative of amplitude values and phase values, the input information being in the form of a stream of data samples; a voltage control unit to provide a variable supply voltage to the RF power amplifier in response to a control signal, the variable supply voltage being selected from a plurality of discrete voltage levels; and a controller to provide the input information to the digital-to-RF modulator and the control signal to the voltage control unit based, at least in part, on data to be transmitted by the RF transmitter, wherein the controller is configured to make decisions about voltage level changes for the RF power amplifier and said decisions are based, at least in part, on the stream of data samples representing data to be transmitted by the RF transmitter and a required instantaneous RF output for an instantaneous sample, wherein the controller is configured to select a discrete voltage level for the RF power amplifier for an instantaneous data sample, with the selection of the discrete voltage level being based, at least in part, on: (a) a required RF output, (b) at least one previous data sample provided to the digital-to-RF modulator in the past, (c) the instantaneous data sample provided to the digital-to-RF modulator, and (d) one or more future data samples to be provided to the digital-to-RF modulator at a point in time after the instantaneous data sample, with the at least one previous data sample, the instantaneous data sample and the one or more future data samples all within a window of data samples N w samples long. an RF power amplifier; a digital-to-RF modulator to generate an RF input signal for the RF power amplifier based on input information indicative of amplitude values and phase values, the input information being in the form of a stream of data samples; a voltage control unit to provide a variable supply voltage to the RF power amplifier in response to a control signal, the variable supply voltage being selected from a plurality of discrete voltage levels; and a controller to provide the input information to the digital-to-RF modulator and the control signal to the voltage control unit based, at least in part, on data to be transmitted by the RF transmitter, wherein the controller is configured to make decisions about voltage level changes for the RF power amplifier and said decisions are based, at least in part, on the stream of data samples representing data to be transmitted by the RF transmitter and a required instantaneous RF output for an instantaneous sample, wherein the controller is configured to select a discrete voltage level for the RF power amplifier for an instantaneous data sample, with the selection of the discrete voltage level being based, at least in part, on: (a) a required RF output, (b) at least one previous data sample provided to the digital-to-RF modulator in the past, (c) the instantaneous data sample provided to the digital-to-RF modulator, and (d) one or more future data samples to be provided to the digital-to-RF modulator at a point in time after the instantaneous data sample, with the at least one previous data sample, the instantaneous data sample and the one or more future data samples all within a window of data samples N w samples long. (a) a required RF output, (b) at least one previous data sample provided to the digital-to-RF modulator in the past, (c) the instantaneous data sample provided to the digital-to-RF modulator, and (d) one or more future data samples to be provided to the digital-to-RF modulator at a point in time after the instantaneous data sample,