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Summary: mi':
iaE
Large-Signal HBT Model with Improved Collector Transit
Time Formulation for GaAs and InP Technologies
Masaya Iwamoto, David E.Root*, Jonathan B. Scott*,Alex Cognata*,
Peter M. Asbeck, Brian Hughes*, and Don C. D'Avanzo*
Dept. of Electrical and Computer Engineering, Univ. of Californiaat San Diego, La Jolla, CA
*MicrowaveTechnology Center, Agilent Technologies, Santa Rosa, CA
Abslracf - An analytical large-signal HBT model which
accurately accounts for the intricate hias dependence of
collector delay in devices fabricated in both GaAs and InP
material systems is described. The strongly hias dependent
collector delay function accounts for the variation of electron
velocity with electric field of the collector, which has
consequences for both the electron transit time and
capacitance. It is shown that the new formulation
significantly improves the prediction of the bias dependence
of fr. As a result, simulations over a very wide range of
operating conditions match measured data ou a wide variety
of devices. Distortion predictions are improved since the
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