A radio frequency transmitter comprising at least one digital power amplifier component and at least one digital signal processing module (410, 710), the at least one digital signal processing module (410, 710) comprising a plurality of digital pre-distortion components (430, 440, 615, 625, 635, 645, 730, 820) and being arranged to: receive a complex digital input signal; successively and sequentially apply pre-distortion to the received complex digital input signal with a progressively finer granularity as the sampling rate of the received complex digital input signal is simultaneously progressively increased; and output a first, in-phase digital control word and a second, quadrature, digital control word for controlling the at least one digital power amplifier component to generate an RF signal representative of the received complex digital input signal, wherein the signal processing module (410,710) further comprises at least one interpolation component (460, 617, 627, 637) operably coupled between sequential pre-distortion components (430, 440, 615, 625, 635, 645, 730, 820) and arranged to: receive a first data rate indication of a sub-set of the pre-distortion profile information (350, 530) output by a preceding pro distortion component (430, 615, 625, 635), perform interpolation of the multiple indications of a sub-set of the pre-distortion profile information (350, 530) output by the preceding pre-distortion component (430, 615, 625, 635); and output at an increased data rate an interpolation indication of a sub-set of the pre-distortion profile information (350, 530) to a successive pre-distortion component (440, 625, 635, 645, 820, 730). receive a complex digital input signal; successively and sequentially apply pre-distortion to the received complex digital input signal with a progressively finer granularity as the sampling rate of the received complex digital input signal is simultaneously progressively increased; and output a first, in-phase digital control word and a second, quadrature, digital control word for controlling the at least one digital power amplifier component to generate an RF signal representative of the received complex digital input signal, wherein the signal processing module (410,710) further comprises at least one interpolation component (460, 617, 627, 637) operably coupled between sequential pre-distortion components (430, 440, 615, 625, 635, 645, 730, 820) and arranged to: receive a first data rate indication of a sub-set of the pre-distortion profile information (350, 530) output by a preceding pro distortion component (430, 615, 625, 635), perform interpolation of the multiple indications of a sub-set of the pre-distortion profile information (350, 530) output by the preceding pre-distortion component (430, 615, 625, 635); and output at an increased data rate an interpolation indication of a sub-set of the pre-distortion profile information (350, 530) to a successive pre-distortion component (440, 625, 635, 645, 820, 730). receive a first data rate indication of a sub-set of the pre-distortion profile information (350, 530) output by a preceding pro distortion component (430, 615, 625, 635), perform interpolation of the multiple indications of a sub-set of the pre-distortion profile information (350, 530) output by the preceding pre-distortion component (430, 615, 625, 635); and output at an increased data rate an interpolation indication of a sub-set of the pre-distortion profile information (350, 530) to a successive pre-distortion component (440, 625, 635, 645, 820, 730).