The new inverted class F mode of operation  is employed for high efficiency operation of E-PHEMT in order to compensate for its low [I.sub.max] compared to the D-PHEMT.
The E-PHEMT delivers 24.5 dBm or 141 mW/mm of output power with associated PAF = 70 percent and small-signal gain of 21.4 dB, compared to 24.8 dBm (151 mW/mm) with associated PAE = 73.5 percent and small-signal gain of 22.6 dB for the D-PHEMT.
The 2 mm E-PHEMT delivers 28.3 dBm or 340 mW/mm of output power with associated PAE = 82 percent, compared to 31 dBm (630 mW/mm) with associated PAE = 85 percent for the D-PHEMT.
A PAE of 70 percent or higher is achieved for the E-PHEMT for the whole range of voltages from 7 to 2 V.
An E-PHEMT features a PAE of 70 percent or higher at operating voltages ranging from 2 to 7 V At 7 V and 900 MHz a state-of-the-art PAE of 85 percent and 630 mW/mm of output power were achieved for the D-PHEMT, while PAE of 82 percent and 340 mW/mm of output power were achieved for the E-PHEMT.