ULTRA-HIGH SPEED AlInAs-GaInAs HEMT TECHNOLOGY.
The authors report on the ultrahigh-speed performance of 15-stage ring oscillators utilizing 0. 2- mu m gate length Al//. //4//8In//. //5//2As-Ga//. //4//7In//. //5//3As HEMTs (high-electron-mobility transistors) fabricated on InP substrates. The AlInAs-GaInAs modulation-doped system is extremely attractive for high-speed digital and analog applications. Fifteen-stage ring oscillators were fabricated using both buffered FET logic (BFL) and capacitively enhanced logic (CEL) schemes and their performance was measured at room temperature (300 K). The shortest gate delay measured for BFL was 9. 26 ps (fanout equals 1) with 66. 7 mW/gate power dissipation. The shortest CEL gate delay was 7. 21 ps (fanout equals 1) at 24. 5 mW. The measured fanout, sensitivities for BFL and CEL are 1. 5 ps and 2. 7 ps per fanout respectively. As expected, CEL gates are faster than BFL gates at low fanout, but CEL is more sensitive to fanout because its output is not buffered.
