An HPSK/OFDM 64-QAM Dual-Mode Doherty Power Amplifier Module for Mobile Terminals

Takayuki KATO

IEICE TRANSACTIONS on Electronics   Vol.E90-C    No.9    pp.1678-1684
Publication Date: 2007/09/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e90-c.9.1678
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Microwave and Millimeter-Wave Technology)
Category: Active Devices/Circuits
Doherty amplifier,  PA module,  HPSK,  OFDM 64-QAM,  multi-mode,  mobile terminal,  GaAs MMIC,  

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This paper presents a miniaturized dual-mode Doherty PA module applicable for an HPSK signal and an OFDM 64-QAM signal. Dual-mode operation with identical hardware is realized by introducing a bias switching technique, which changes bias conditions of amplifiers according to transmission signals, and employing dual-mode matching circuits, which are designed based on the results of load-pull measurements using an HPSK signal and an OFDM 64-QAM signal. The Doherty PA module consists of a Doherty stage and a gain stage. Two GaAs-HBTs for a Doherty stage and one GaAs-HBT for a gain stage are integrated onto a 1 mm-square single GaAs-MMIC. In the HPSK mode, maximum output power of 26.7 dBm, power added efficiency (PAE) of 41%, and power gain of 27 dB are obtained in the condition that adjacent channel leakage power ratio (ACLR) is under -38 dBc. In the OFDM 64-QAM mode, maximum output power of 21.0 dBm, PAE of 27%, and power gain of 28 dB are obtained under EVM < 3.0%. This is the first multi-mode Doherty PA module suitable for multi peak to average power ratio (PAPR) signals.