Optimizing CMOS amplifier design directly in SPICE without the need for additional mathematical models

This paper presents a method that optimizes the performance of CMOS amplifiers with respect to gain, bandwidth, noise, distortion and power. The method is performed directly in SPICE without the aid of mathematical models or external software routines. The method works in all SPICE programs from Cadence to the student version of PSPICE. The technique is based on tuning the voltage of specific nodes of the amplifier using a servo-loop biasing technique in conjunction with a replica amplifier circuit to span the entire performance space with a resolution of choice. Both single-stage and multi-stage amplifiers are considered in this work.