Cryogenic small-signal model for 0.55 mu m gate-length ion-implanted GaAs MESFET's

The cryogenic microwave performance of 0.5*300- mu m gate ion-implanted GaAs MESFETs is presented. The devices studied have been fabricated as part of a process control monitor chip (PCM) which uses comparable industry standard design rules. Detailed small-signal element modeling has been performed to determine the temperature dependence of important physical parameters over a lattice temperature range from 300 K to 115 K. The authors find appreciable improvement in cut-off frequency (f/sub T/) and well behaved temperature dependence of transconductance (g/sub m/) and gate-source capacitance (C/sub gs/). Empirical relations for the temperature dependence of f/sub T/, the maximum frequency of oscillation (f/sub max/), g/sub m/ and C/sub gs/, that should provide accurate temperature-dependent device and circuit models are presented.<
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