PAE enhancement by intermodulation cancellation in an InGaP/GaAs HBT two-stage power amplifier MMIC for W-CDMA

We developed an InGaP/GaAs heterojunction bipolar transistor (HBT) two-stage power amplifier monolithic microwave integrated circuit (MMIC) for 1.95-GHz W-CDMA. In this MMIC, intermodulation distortion (IMD) cancellation between the driver- and final-stage HBTs occurs, so we can reduce an adjacent-leakage-power-ratio (ACPR) and enhance power-added efficiency (PAE) by balancing the bias currents for each stage. The MMIC has a high PAE of 44%, an output power of 26.0 dBm, and a gain of 27.9 dB with ACPR of -35 dBc at a 5-MHz offset frequency under a supply voltage of 3.6 V. This PAE represents state-of-the-art performance of HBT MMICs for W-CDMA.