Power amplifiers for 3.5 GHz W-CDMA applications

The InGaAs PHEMT is attracting good interest as a cost effective, highly reliable power amplifier technology for base station applications. Operating from 12 V supplies, a typical 15 mm device delivers over 40 dBm of saturated power with efficiencies as high as 68% at 1.9 GHz and 58% at 3.5 GHz. Under the stringent W-CDMA spec of -40dBc adjacent channel power (with 11.2 dB peak-to-average signal ratio), a linear power of 33.0 dBm with 28.5% efficiency is obtained in class AB mode. In this paper, we discuss the design, fabrication and rf performance of InGaAs PHEMT PAs under development for low cost, highly linear basestation applications.