On the Importance of Initial Sizing of Analog Circuits Based on Analytical Equations

In this paper, we investigate the role and benefits of initial sizing in the analog circuit sizing process, particularly when complemented by an optimization routine for nominal optimization. Our findings show that, on average, and for technologies down to 45 nm, optimization routines substantially benefit from initial sizing based solely on Shichman-Hodges models. Leveraging an automated tool for initial sizing based on analytical design equations, we generate a diverse array of start points for different specifications. Initial sizing is combined with a constrained nominal optimization from an industry-standard tool that relies on numerical simulation. Across several designs and various specifications, we reach an average reduction of 50–65 percent in the number of simulations required when using the automatic initial sizing based on analytical equations. All results were obtained for a comprehensive set of performance measures.