@article {Laser1991Reconciliation-,
title = {Reconciliation of methods for estimating fmax for microwave heterojunction transistors},
journal = {Electron Devices, IEEE Transactions on},
volume = {38},
number = {8},
year = {1991},
month = {aug.},
pages = {1685 -1692},
abstract = {An attempt is made to reconcile the various approaches that have recently been used to estimate the maximum frequency of oscillation fmax in high-performance AlGaAs/GaAs HBTs. fmax is computed numerically from the full expression for Mason{\textquoteright}s invariant gain using y-parameters derived from the different approaches, i.e., the hybrid- pi; equivalent circuit, the T-equivalent circuit, and the drift-diffusion equations. It is shown that the results for fmax 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 fmax, involving f T and effective base resistance and collector capacitance, is remarkably accurate for frequencies below those at which transit-time effects become important},
keywords = {AlGaAs-GaAs, aluminium compounds, analytical expression, collector capacitance, drift-diffusion equations, effective base resistance, equivalent circuit, equivalent circuits, fT, gallium arsenide, HBTs, heterojunction bipolar transistors, hybrid- pi, III-V semiconductors, Mason{\textquoteright}s invariant gain, maximum frequency of oscillation estimation, microwave heterojunction transistors, semiconductor device models, semiconductors, solid-state microwave devices, T-equivalent circuit, transit-time effects, y-parameters},
issn = {0018-9383},
doi = {10.1109/16.119002},
url = {http://dx.doi.org/10.1109/16.119002},
author = {LASER, AP and Pulfrey, D L}
}