42% high efficiency two-stage HBT power amplifier MMIC for W-CDMA cellular phone system

This paper is the first to report a high efficiency two-stage HBT power amplifier MMIC for 1.95GHz wide-band CDMA (W-CDMA) cellular phone system. Power amplifiers for W-CDMA system are required with high efficiency and high linearity over a wide range of output power level. To obtain a high efficiency, we chose a near class B operation. To obtain a high linearity, we suppressed the gain distortion due to a near class B operation by the adaptive biasing technique. The MMIC exhibited the highest power-added efficiency (PAE) of 42% ever reported, a Cain of 30.5 dB, and in adjacent channel leakage power ratio (ACLR) at a 5 MHz offset frequency of - 38 dBc at a Pout of 27 dBm under a supply voltage of 3.5 V with 3.84 Mcps HPSK modulation.