A 2.14-GHz Chireix outphasing transmitter

A Chireix outphasing system for 2.14 GHz including two saturated class-B pseudomorphic high electron-mobility transistor power amplifiers (PAs) and a Chireix power-combining circuit is reported in this paper. In an outphasing system, an arbitrary input signal is divided into two constant envelope branches. The phase-only modulated branches are then amplified with high-efficiency nonlinear PAs. By controlling the phases of these branches, the original signal waveform can be reconstructed, ideally with high efficiency and perfect linearity. In this paper, the design and implementation of an experimental Chireix outphasing system for a wide-band code division multiple access 2.11-2.17-GHz downlink band is presented. The measured system efficiency for 7-dB backed-off quadrature phase-shift keying signal was 42.2% with a channel power of 31.2 dBm.