Supply modulators for RF polar transmitters

This paper summarizes the advantages of PA linearization via polar modulation and illustrates the necessity for high-performance supply modulators in polar transmitters. Two potential modulator solutions are introduced; both having between 4 MHz and 20 MHz occupied RF bandwidth and more than 65 dB SFDR. These modulators process envelope information for 1625 kb/s 8PSK and CDMA IS95 applications in polar PA architectures. The presented circuits and signal processing techniques can be generalized for future modulator designs.