Enhancement Mode PHEMT for Single Supply High Efficiency Power Amplifiers

An enhancement mode power PHEMT technology is demonstrated as a viable alternative to an HBT for single supply high efficiency power amplifiers. The newly developed E-PHEMT has Idss=0.5 ¿A/mm, Imax=190 mA/mm, Vp=+0.3 V, Gm=340 mS/mm and Vbdg=20 V. Various on-wafer loadpull results at 900 and 1800 MHz are presented. A 315 mW/mm output power with PAE=76.4% is demonstrated at 1800 MHz and 4V, while 37 mW/mm and PAE=71% is achieved at 900 MHz and 1.5V. These state of the art results for any single-supply technology were achieved by utilizing systematic harmonic loadpull measurements in conjunction with accurate large-signal modeling.