To make Mextram represent a given transistor, one needs to assign appropriate values to the parameters of the model. Parameter extraction is the procedure for obtaining an appropriate set of values for the parameters for any given transistor.
All Mextram model parameters can be extracted in a step-by-step procedure from measured data. Strategies for extraction of parameter values can be found in the Mextram documentation page.
Parameter extraction is an important part in the whole process of using a compact model. A general way of extracting parameters for Mextram is described. This includes a description of the measurements that have to be taken.
To support obtaining a good set of high-current parameters for bipolar transistors, not only a parameter extraction method is presented, but also the influences of parameters on characetristics is shown. This information has proved to be useful in practise.
A separate chapter is devoted to the extraction of the parameters that belong to temperature scaling.
Because the geometry of bipolar transistors is diverse in practise, predefined geometrical scaling rules are not part of the Mextram model. Based on its physical fundamentals however, Mextram is formulated such that formulation of geometrical scaling rules for any given transistor technology is usually straightforward. In the parameter extraction documentation, we present the basics for geometric scaling together with a way to extract the corresponding parameters. Statistical modelling is briefly discussed.
The way how this parameter extraction strategy is implemented in the program IC-CAP of Agilent is discused.