Subtleties of SPICE MOSFET parameter extraction

Circumvention of problems in both DC and AC MOSFET SPICE parameter measurement and extraction is discussed. The goals of this study are to point out pitfalls in extracting accurate and self-consistent SPICE MOS model parameters and, where possible, provide procedures for circumventing the difficulties. To this end, the author provides a fully functional method for extracting DC model parameters and and methods for obtaining the junction and overlap capacitance parameters; appropriate test structures and measurement techniques as well as some of the more subtle aspects of skew model generation are also covered. Test chip layout and least-squares fitting methods are discussed. Emphasis is placed on accuracy and self-consistency.