Digital Control of Power Amplifiers for Wireless Communications

Abstract

The advance of CMOS-based digital circuits enables new strategies for optimisation of wireless transmitters. Codesign of DSP algorithms and power amplifier characteristics can lead to improved efficiency and linearity through a variety of strategies, including: a) DSP control over bias conditions, particularly the power supply voltage; b) predistortion, in simple amplifiers, and in compound architectures such as LINC and Doherty amplifiers; and c) DSP generation of digital input signals for switching amplifiers. We envision for the future a generation of "smart power amplifiers" in which DSP optimization of amplifier parameters is carried out for changing environments.

Analysis of Non-Uniform Polar Quantisers in a Sigma Delta Transmitter Architecture

“…Switch mode PAs require on an 'on' and 'off' drive signal and this gives the opportunity of digital control. Since process technology has improved, it is therefore now possible to directly generate a modulated IF or RF signal from a digital source with frequencies ranging from tens MHz up to the low GHz [2]- [3]. This paper considers the replacement of the traditional direct up-conversion architecture by a digital architecture.…”