[Delta][Sigma] digitised polar transmitter with CMOS switching power amplifier

A 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.