Automatic Initial Sizing of Operational Amplifiers with Support of Weak, Moderate and Strong Inversion

Abstract:
This paper presents a method to automatically size op-amps using simple transistor models. A constraint program based on analytical formulas is used to initially size the op-amps which emulates the manual analog design process. While analytical equations are used to model the transistors in weak and strong inversion, the gm/Id-method based on look-up tables is used for the transistor model in moderate inversion. Experimental results are presented for an op-amp with transistors in the three inversion regions.