Experience with the new compact MEXTRAM model for bipolar transistors

Abstract

The improved performance of the compact bipolar transistor model MEXTRAM is demonstrated by comparison with Gummel-Poon (GP) model calculations and measured DC and high-frequency data. The MEXTRAM model contains extended modeling of the collector epilayer and the inactive region of the base-collector epilayer and the parasitic pnp. It has five internal nodes, whereas the GP model has three. The advantage is a more accurate prediction of the DC behavior and the f/sub t/ fall-off at high currents. The AC small-signal behavior at frequencies >or=f/sub t/ is dominated by the inactive part of the device. If unphysical fit parameters are accepted, the GP model can obtain in the forward mode up to the top of the f/sub t/ nearly as good a fit as MEXTRAM does; the predictive capability, especially for down-scaled devices, however, will remain inferior. This is a very important point for circuit optimization MEXTRAM has been used successfully in this area, e.g. for ECL gates. >