Analysis and Design of Small-Signal Polar Transmitters for

Abstract

In cellular applications, open-loop small-signal polar transmitters offer several advantages such as low power consump- tion and small silicon area. However, due to their complexity, circuit imperfections can severely affect performance, potentially rendering them impractic al to meet the challeng ing cellular transmitter requirements. In this paper a detailed analysis of the direct-modulated and small-signal polar transmitters for GSM/EDGE/WCMA applications are provided fo llowed by some case studies. Several key non-idealities will be discussed and circuit level as well as architectural remedies for each will be presented. A prototype EDGE transmitter fabricated i n6 5n mC M O Sw i t h an 8PSK 400 kHz modulation spectrum of 64/63 dBc for high/low bands, and an RMS EVM of 2.5/2.0% will be discussed.