PCS/W-CDMA dual-band MMIC power amplifier with a newly proposed linearizing bias circuit

TLDR

The authors present a dual‑band PCS/W‑CDMA MMIC power amplifier that incorporates a novel on‑chip linearizer to improve linearity while maintaining a single‑chip, single‑path output matching network. The linearizer uses the base‑emitter diode of an active bias transistor in series with a capacitor to short the base node at RF, and the amplifier is built on an InGaP HBT MMIC with single input/output and no band‑switching, providing broad‑band performance. The integrated linearizer boosts the 1‑dB compression point by 18.5/20 dB and reduces phase distortion by 6.1/12.42 deg/ at 28 dBm, achieving 30/28.5 dBm output power, 39.5/36 % PAE, and –46/–50 dBc ACPR at 3.4 V for PCS/W‑CDMA bands with negligible power loss and die area increase.

Abstract

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/spl deg/ (12.42/spl deg/) 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.