A fully selective double-recess enhancement mode PHEMT process for linear and saturated power amplifiers

Performance of a fully selective wet chemical etch enhancement mode PHEMT (E-PHEMT) process for 900 MHz saturated and linear power amplifiers (PA´s) is presented. Typical device IV characteristics of this device include Idss=50 μA/mm, Imax=270 mA/mm, Gm=330 mS/mm. Breakdown voltage was above 25 V at Ig=0.1 mA/mm. At 900 MHz and 3.2 V a 5 mm E-PHEMT delivered 27 dBm (100 mW/mm) with PAE=70%, while a 2 mm E-PHEMT delivered 16.5 dBm (21 mW/mm) of linear output power with PAE=40% and adjacent and alternate channel power ratios (ACPRI and 2) of -48 and -60 dBc, respectively, which meets the IS-98 CDMA requirements. Very good parameter uniformity across the wafer was achieved due to the fully selective nature of the process