POWER HETEROJUNCTION FETS FOR LOW-VOLTAGE DIGITAL CELLULAR APPLICATIONS

This paper describes 950 MHz power performance of double-doped AlGaAs/ InGaAs/AlGaAs helerojunction field-effect transistors (HJFET) operated al a drain bias voltage ranging from 2.5 to 3.5 V. The developed 1.0 mu m gate-length HJFET exhibited a maximum drain current (I-max) of 50 0 mA/mm, a transconductance (g(m)) of 300 mS/mm, and a gate-to-drain b reakdown voltage of 11 V. Operated at 3.0 V, a 17.5 mm gate periphery HJFET showed 1.4 W P-out and - 50.3 dBc adjacent channel leakage power at a 50 kHz off-carrier frequency from 950 MHz with 50% PAE. Harmonic balance simulations revealed that the flat g(m) characteristics of th e HJFET with respect to gate bias voltage are effective to suppress in termodulation distortion under large signal operation. The developed H JFET has great potential for small-sized digital cellular power applic ations operated at a low DC supply voltage.