Abstract

This paper describes the recent development of GaAs MMICs for wireless communication systems such as the digital cellular phone, the satellite communication system, the local area network and the automatic radar system. The InGaP-emitter heterojunction bipolar transistor (HBT) for the 1.5-GHz digital cellular phones exhibited the output power of 31dBm at 1.5 GHz with the power-added efficiency of 68.8% and the adjacent channel power (ACP) of - 48 dBc at 50 kHz offset. The GaAs microwave signal processor developed for the 2.5-GHz active phased array antenna aboard the satellite has one thousand circuit-elements which is 100 times higher than conventional MMIC's. The 60-GHz 4-stage buffer-amplifier MMIC newly designed for a cost-effective local area network can offer the |s12|2 of less than-38 dB and the |s21|2 of larger than 17 dB at 60 GHz. The InGaP/ InGaAs/ GaAs HEMT with the 0.15- um gate and the flip chip structure was developed for the 76-GHz automotive radar system. The two-stage amplifier MMIC provides the small-signal gain of 10.6 dB at 76.5 GHz.