A new performance measure, based on the capability indices C/sub p/ and C/sub pk/ (commonly used in process control), is proposed for general circuit Design for Quality. It overcomes some of the critical limitations of the traditional quadratic loss function (e.g., that of Taguchi) and leads to the creation of a new methodology for statistical circuit design. It also allows for the automation of the manual two-stage variability minimization/tuning methodology, and gives a concrete interpretation to the "goodness" of a circuit in easy to understand terms. Successful IC variability/performance optimization examples are presented.>

An interpolation scheme (maximally flat quadratic interpolation (MFQI) and an approximation scheme (group method of data handling (GMDH)) are combined to obtain a novel heuristic approximation method. This composite structure overcomes the shortcomings of the individual methods while maintaining their desirable features. The combined method is efficient and much more accurate than either of the two individual schemes. This is the case especially when the functions being approximated are complex within the input variable range specified. Several analog and digital circuit examples, in addition to a variability minimization example for a delay circuit, demonstrate the utility of the proposed approach.>