Mixed Cartesian feedback for Zero-IF WCDMA transmitter

In this paper, a new adaptive power amplifier (PA) linearization technique is presented. The idea is to consider a classic WCDMA Zero-Intermediate Frequency (Zero-IF) transmitter with a modified Cartesian feedback (CFB) loop. The new transmitter architecture consists of an analog stage including forward I/Q modulator and feedback I/Q demodulator and a digital stage adjusting the phase rotation around the loop. The digital phase-alignment system consumes 2.94 mW (tree time less than a full-analog system).