A Cartesian feedback feasibility study for a zero-IF WCDMA transmitter handset IC

Abstract

A Cartesian feedback feasibility study is presented describing the main requirements of a WCDMA zero-IF transmitter IC. The transmitter architecture consists of an analog part with a forward modulator, a feedback demodulator and a digital part to adjust the phase rotation around the loop and to remove the DC offset and I/Q gain mismatches in the feedback path. Linearization performances are 27 dB ACPR improvement at 5 MHz offset and 15 dB ACPR improvement at 10 MHz.