A HIGHER LEVEL MODELING PROCEDURE FOR ANALOG INTEGRATED-CIRCUITS

A step-by-step procedure for creating higher levels models for analog integrated circuits is presented and illustrated. The procedure begins with a SPICE level circuit description and generates a model consisti ng of linear and nonlinear differential equations. The modeling method provides many avenues for trading simulation speed for accuracy. The procedure is described and illustrated on an analog voltage comparator and a high-dynamic-range CMOS operational amplifier. It is possible t o achieve time domain errors on the order of 10% or less on such chara cteristics as settling time and propagation delay. The simulation time is typically improved by a factor of 10 to 30 while retaining the pre scribed accuracy. This paper is intended to convey a methodical, algor ithmic approach for developing higher level models of analog circuits that can be applied by hand.