A Doherty power amplifier module for mobile terminals with variable linearity function

A Doherty power amplifier (PA) module for mobile terminals with variable linearity function has been developed. The linearity of the Doherty PA module is optimized according to transmission signals by a bias switching technique. The Doherty amplifier module consists of a gain amplifier and a Doherty amplifier. One GaAs HBT for a gain amplifier and two GaAs HBTs for a Doherty amplifier are integrated onto a single GaAs MMIC (1.0 mm × 1.0 mm × 0.1 mm) chip. The module achieved 26.7 dBm output power with less than - 38dBc adjacent channel leakage power ratio (ACLR) in W-CDMA uplink mode, and 21 dBm output power with less than 3.0 % error vector magnitude (EVM) was obtained in orthogonal frequency division multiplexing (OFDM) 64-QAM-mode. The developed Doherty PA module is suitable for a multi-mode terminal including various high peak-to-average power ratio (PAPR) signals such as code division multiple access (CDMA) and OFDM.