A telecommunications system transmitter circuit, comprising: a digital modulator for receiving a digital source information signal, generating intermediate data streams from the received digital source information signal, wherein the intermediate data streams comprise an in-phase component and a quadrature component, and generating a modulated information signal from the intermediate data streams comprising the in-phase component and the quadrature component; an envelope computation block, coupled to the digital modulator, for determining an envelope of the digital source information signal from the intermediate data streams and generating a dynamic input bias signal as a function of the envelope of the digital source information signal; combining and conversion circuitry (504, 512, 506), coupled to the digital modulator and the envelope computation block, for converting to analog form and combining the modulated information signal and the dynamic input bias signal to output an analog signal suitable to be applied to an input of a power amplifier; and a pre-distortion block, coupled between the envelope computation block and the combining and conversion circuitry, for applying a transform function to the envelope of the digital source information signal to generate a pre-distorted envelope (E'), such that the dynamic input bias signal is a pre-distorted dynamic input bias signal, wherein: the transform function is configured to apply a first pre-distortion level for envelope levels below a selected threshold, and a second pre-distortion level, less than the first pre-distortion level, for envelope levels above the selected threshold; or the transform function is applied only to envelope levels below a selected threshold, the telecommunications system transmitter circuit comprising the power amplifier having said input for receiving and amplifying the analog signal to modulate the current through the power amplifier as a function of the envelope, and a power terminal for receiving a supply voltage, wherein the combining and conversion circuitry is coupled to said input of the power amplifier. a digital modulator for receiving a digital source information signal, generating intermediate data streams from the received digital source information signal, wherein the intermediate data streams comprise an in-phase component and a quadrature component, and generating a modulated information signal from the intermediate data streams comprising the in-phase component and the quadrature component; an envelope computation block, coupled to the digital modulator, for determining an envelope of the digital source information signal from the intermediate data streams and generating a dynamic input bias signal as a function of the envelope of the digital source information signal; combining and conversion circuitry (504, 512, 506), coupled to the digital modulator and the envelope computation block, for converting to analog form and combining the modulated information signal and the dynamic input bias signal to output an analog signal suitable to be applied to an input of a power amplifier; and a pre-distortion block, coupled between the envelope computation block and the combining and conversion circuitry, for applying a transform function to the envelope of the digital source information signal to generate a pre-distorted envelope (E'), such that the dynamic input bias signal is a pre-distorted dynamic input bias signal, wherein: the transform function is configured to apply a first pre-distortion level for envelope levels below a selected threshold, and a second pre-distortion level, less than the first pre-distortion level, for envelope levels above the selected threshold; or the transform function is applied only to envelope levels below a selected threshold, the telecommunications system transmitter circuit comprising the power amplifier having said input for receiving and amplifying the analog signal to modulate the current through the power amplifier as a function of the envelope, and a power terminal for receiving a supply voltage, wherein the combining and conversion circuitry is coupled to said input of the power amplifier.