Automating analog circuit design using constrained optimization techniques

A CAD (computer-aided design) tool that accurately sizes analog circuits in short-channel CMOS processes using SPICE-quality device models and constrained optimization techniques is presented. All knowledge about device behavior is embedded within an encapsulated device evaluator which simplifies the description of the analog circuit that must be provided by an expert designer, and makes that description independent of the specific device type and technology. The use of constrained optimization allows the KCL and KVL constraints that determine the DC operating point of a circuit to be formulated and solved simultaneously with the performance constraints. In addition, the constrained optimization formulation of the analog design problem makes it easy for the user to study tradeoffs in the circuit design space by varying the performance constraints. Simulation results demonstrate the tool´s ability to accurately synthesize high-performance two-stage CMOS op amps in 2 mu m and 1.2 mu m CMOS processes.<>