1.2 V operation power heterojunction FET's for digital cellular applications

This paper describes 950 MHz power performance of 1.2 V drain bias operation n-AlGaAs/InGaAs/n-AlGaAs heterojunction FET's (HJFET) for personal digital cellular (PDC) applications. The fabricated HJFET with a 0.8-/spl mu/m long WSi gate exhibited an on-resistance (/spl tau//sub 0n/) of 2.1/spl Omega//spl middot/mm and a maximum drain current of 640 mA/mm. Operated at 1.2 V drain bias voltage, the HJFET with gate width of 28.0 mm demonstrated an output power of 30.0 dBm (1.0 W) and a power-added efficiency of 51.5% with an adjacent channel leakage power at 50 kHz off-center frequency of -50.8 dBc. Class A operation analysis, which shows a good coincidence with the measured PDC power performance, revealed that the excellent power performance with the relatively small gate width was due to the low /spl tau//sub 0n/ of the fabricated HJFET.