Fuzzy Techniques in Optimization - Based Analog Design

Cell-level analog circuit design is a very challenging task for several reasons: the design problem is usually underconstrained with many degrees of freedom, most analog modules require a custom optimized design, the performance requirements must be traded off as they usually are competing design objectives, to encounter the most important ones. This paper presents some applications of fuzzy techniques in the design of analog modules. Our research direction turns into account the opportunities offered by fuzzy techniques in the optimization-based design of analog circuits field. In our approach, all the phases of the optimization process involve fuzzy methods. Fuzzy sets are involved in the formulation of the optimization objectives and in the initial guess of the design parameters, while some fuzzy systems address the performance evaluation issues (evaluation engine) and new parameter values computation (optimization engine). Two CAD tools at the cell level were developed in Matlab. The operation of these CAD tools is validated by a large collection of experimental results. Basic analog modules as simple transconductance operational amplifier, Miller operational transconductance amplifier, and common-emitter stage were designed for several sets of design requirements with very good results. Key-words: Analog design, Multiobjective optimization, Fuzzy sets, Fuzzy systems, Unfulfillment degree.