Polar transmitter for wireless communication system

Polar modulation techniques offer the capability of multimode wireless system and the potential for the high efficiency power amplifier (PA). Any input baseband complex signal is decomposed into magnitude and phase signal, and goes through envelope modulator and phase modulator respectively. The modulated envelope and phase message signals are combined and amplified by switched-mode PA. In this paper, we will focus on the rectangular-to-polar converter, envelope modulator and phase modulator of polar transmitter for EDGE (2.5G) system. The analog part includes open-loop envelope modulator. The digital part includes rectangular-to-polar converter and digital phase modulator. We employ the coordinate rotation digital computer (CORDIC) and direct digital frequency synthesizer (DDFS) techniques in this part. A prototype chip has been designed and fabricated in UMC 0.18 μm CMOS process with 1P6M technology.