Delta Sigma digitised polar transmitter with CMOS switching power amplifier

Abstract

A delta-sigma (Delta Sigma) digitised polar RF transmitter with a CMOS switching power amplifier is presented. The proposed power amplifier consists of a class-E amplifier with a modulating current source which allows high efficiency and high linearity. A current source is introduced in the proposed power amplifier to achieve Delta Sigma digitised amplitude modulation. The current mode amplitude modulation is suitable for a high speed modulated signal such as an oversampled Delta Sigma signal.