%0 Journal Article
%J IEEE Trans. Electron Devices (USA)
%D 1991
%T Reconciliation of methods for estimating *f*_{max} for microwave heterojunction transistors
%A Laser, A P
%A Pulfrey, D L
%K aluminium compounds;equivalent circuits;gallium arsenide;heterojunction bipolar transistors;III-V semiconductors;semiconductor device models;solid-state microwave devices;
%P 1685 - 92
%U http://dx.doi.org/10.1109/16.119002
%V 38
%X An attempt is made to reconcile the various approaches that have recently been used to estimate the maximum frequency of oscillation *f*_{max} in high-performance AlGaAs/GaAs HBTs. *f*_{max} is computed numerically from the full expression for Mason's invariant gain using *y*-parameters derived from the different approaches, i.e., the hybrid-π equivalent circuit, the T-equivalent circuit, and the drift-diffusion equations. It is shown that the results for *f*_{max} are essentially the same, irrespective of the source of the *y*-parameters, provided that the phase delays due to transit of carriers across the base and the collector-base depletion region are properly accounted for. It is also shown, for the particular device studied, that the widely used analytical expression for *f*_{max}, involving *f*_{T} and effective base resistance and collector capacitance, is remarkably accurate for frequencies below those at which transit-time effects become important
%Z semiconductors;maximum frequency of oscillation estimation;microwave heterojunction transistors;HBTs;Mason's invariant gain;y-parameters;hybrid-π equivalent circuit;T-equivalent circuit;drift-diffusion equations;analytical expression;f_{T};effective base resistance;collector capacitance;transit-time effects;AlGaAs-GaAs;
%9 article