CMOS op-amp power optimization in all regions of inversion using geometric programming

Abstract

In this paper Geometric Programming is successfully applied to the power optimization of CMOS operational amplifiers using a model valid in all regions of inversion (weak, moderate and strong), which assures a true globally optimal design. A complete transistor model presents some problems on the formulation of the Geometric Program. We will show in this paper that in the case of power optimization, a careful analysis of the physical meaning of the conicting model equations, allow us to overcome these problems in a simple and efficient way. The proposed algorithm is tested in several cases for a Miller amplifier, showing how the optimum inversion level spans all the inversion regions as the target bandwidth changes