A CAD tool for analog circuit synthesis is presented. This tool, called FASY, uses fuzzy–logic based reasoning to select one topology among a fixed set of alternatives. For the selected topology, a two–phase optimizer sizes all elements to satisfy the performance constrains minimizing a cost function. In FASY, the decision rules used in the topology selection process are introduced by an expert designer or automatically generated by means of a learning process that uses the optimizer mentioned above. The capability of learning topology selection rules by experience, is unique in FASY. Practical examples demonstrate the tool ability of this tool to learn topology selection rules and to synthesize analog cells with different circuit topologies. 1 1

Although many design tools have been developed for digital design, analog design tools are only just being introduced. This paper presents a new optimization method for automatically sizing the circuit topology of analog cells. This method minimizes a cost function, which depends on a set of designer specifications. It employs the tabu search heuristic to avoid being trapped in a local minimum of the cost function. Experimental results show that this method can get very close to the global minimum of the cost function with a small number of iterations. Hence, an analog simulation program, such as SPICE, can be used for the evaluation of the cost function at each iteration. I. INTRODUCTION There is an increasing trend towards the integration of analog blocks in ASIC circuits. Despite the great effort that has been made in the development of CAD tools for analog and mixed circuits, the design of the analog part of a chip continues to be a bottleneck [1]--[2]. Different optimization tec...