Realistic Design Using Large-Change Sensitivities and Performance Contours

Two design concepts are discussed which have been implemented as new computer-aided design tools. The first concept is that of large-change sensitivities which are a significant departure from the classical first-order sensitivities. The second concept is that of a performance contour which is, in effect, a second-order largechange sensitivity. The information provided by large-change sensitivities and performance contours is applicable in the phase of design after an acceptable nominal design has been found. Applications of this information to desensitize a design, to specify tolerances, and to indicate parameter correlation with respect to the performance criteria are discussed. The correlation information is useful not only in specifying tuning component matching but also in determining whether a design is consistent with expected statistical correlations in manufacture or in the field. Two real-world examples, some useful properties of contours, and a brief description of the program are included.