OVERVIEW

It is obvious that at the end, uncertainties and errors in measurement-extracted parameters limit the accuracy of a model. Therefore, even a model that can describe a device perfectly may show poor performance because the parameter extraction from measurements is erroneous.

Unfortunately, it depends on the specific device under investigation whether an extraction procedure is applicable or not. Some procedures (e.g., the open-collector measurement) rely on special bias points in order to simplify the equivalent circuit. The underlying assumptions might not hold if the device topology, or the epitaxial layer design, differ too much from the "standard" device the routine was developed for. Maybe the device under test cannot be operated at such high currents as required for a certain measurement. Or an intrinsic parameter extraction algorithm assumes that not only are the values within a certain order of magnitude, but also the ratios between these parameters.

Although the methods presented in this chapter have proven to work well with a broad range of technologies, it is commonly required to adjust the methodology to a specific device.

Parameter sets, like models, have a limited scope of validity. Hence, when determining the parameters, one should have a clear picture of the circuits and operation modes they are to be used for. Also, it should be known within which bounds the model can be considered accurate.

Numerous strategies can be applied in order to determine the parameters of a large-signal model. In principle it is possible to determine the full set...