A predistorted mobile phone base station transmitter with reduced digital subsystem dynamic range requirements

摘要

A mobile phone base station transmitter amplifier 10 is linearised by an adaptive digital predistortion system 1,3. When the amplitude of the digital input signal D is low, the gain of the digital amplitude control block 15 is raised and the setting of the analogue amplitude control block is reduced, thereby maintaining a constant overall system gain but reducing dynamic range requirements for the DAC 8 and digital upconverter 6. When the input signal amplitude is below a first threshold, the adaptive updating of predistortion coefficients is disabled, and when it falls below a lower second threshold, the predistortion updating remains disabled and inverse control of the digital and analogue amplitude control blocks commences. The analogue control block may be an attenuator.