FPAD - A FUZZY NONLINEAR-PROGRAMMING APPROACH TO ANALOG CIRCUIT-DESIGN

FPAD, a CAD tool for the design of analog circuits, is presented, For a set of input specifications, FPAD deduces the device sizes that opti mize the performance objectives while satisfying the constraint specif ications. Fuzzy set theory is used to measure the degree of fulfillmen t of the objectives and constraints, and hence provides a measure of t he design quality. Trade-offs are handled by manipulating the shape of the membership functions that reflect the fulfillment or violation of the performance specifications, FPAD allows the optimization of sever al objectives simultaneously since multiple objective optimization is used. The mathematical formulation of the design problem is fuzzified to support real-world terms like high, good, small, acceptable, etc. T he optimization is based on analytic models to avoid a simulator in th e inner optimization loop. Using this approach, a two-stage unbuffered CMOS op amp and a simple emitter follower were designed, with promisi ng results.