High efficiency power amplifier module with novel enhancement-mode heterojunction FETs for wide-band CDMA handsets

A 0.1 cc high efficiency power amplifier multi chip module (MCM) employing novel enhancement-mode double-doped AlGaAs/InGaAs/AlGaAs heterojunction FETs (HJFET) has been successfully developed for 1.9 GHz wide-band CDMA handsets. The HJFET has a 5 nm thickness Al/sub 0.5/Ga/sub 0.5/As barrier layer for improving a gate forward turn-on voltage. It was also optimized with thickness of upper and lower Al/sub 0.2/Ga/sub 0.8/As electron supply layers to obtain a high maximum drain current. Under single 3.5 V operation, the MCM exhibited 26.0 dBm output power, a record 47.2% power-added efficiency and 22.3 dB associated gain with -35.5 dBc adjacent channel leakage power ratio at 5 MHz off-center frequency.