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A personal communications service/wide-band code division multiple access (PCS/W-CDMA) dual-band monolithic microwave integrated circuit (MMIC) power amplifier with a single-chip MMIC and a single-path output matching network is demonstrated by adopting a newly proposed on-chip linearizer. The linearizer is composed of the base-emitter diode of an active bias transistor and a capacitor to provide an RF short at the base node of the active bias transistor. The linearizer enhances the linearity of the power amplifier effectively for both PCS and W-CDMA bands with no additional dc power consumption, and has negligible insertion power loss with almost no increase in die area. It improves the input 1-dB gain compression point by 18.5 (20) dB and phase distortion by 6.1 (12.42) at an output power of 28 (28) dBm for the PCS (W-CDMA) band while keeping the base bias voltage of the power amplifier as designed. A PCS and W-CDMA dual-band InGaP heterojunction bipolar transistor MMIC power amplifier with single input and output and no switch for band selection is embodied by implementing the linearizer and by designing the amplifier to have broad-band characteristics. The dual-band power amplifier exhibits an output power of 30 (28.5) dBm, power-added efficiency of 39.5% (36%), and adjacent channel power ratio of 46 (50) dBc at the output power of 28 (28) dBm under 3.4-V operation voltage for PCS (W-CDMA) applications.

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We propose a Ku‐band driver and high‐power amplifier monolithic microwave integrated circuits (MMICs) employing a compensating gate bias circuit using a commercial 0.5 μm GaAs pHEMT technology. The integrated gate bias circuit provides compensation for the threshold voltage and temperature variations as well as independence of the supply voltage variations. A fabricated two‐stage Ku‐band driver amplifier MMIC exhibits a typical output power of 30.5 dBm and power‐added efficiency (PAE) of 37% over a 13.5 GHz to 15.0 GHz frequency band, while a fabricated three‐stage Ku‐band high‐power amplifier MMIC exhibits a maximum saturated output power of 39.25 dBm (8.4 W) and PAE of 22.7% at 14.5 GHz.