Design of CMOS opamp using Potential Distribution Method

This paper demonstrates the design of CMOS operational amplifiers (opamp) using Potential Distribution Method (PDM). PDM is a design technique for analog circuits and is based on the principle of voltage distribution between the supply rails of a circuit. Apart from being process independent, it is free from complex mathematical expressions associated with the devices and the circuit. Instead of analytical methods, PDM directly uses the simulator as a device sizing tool to meet the desired performance. This is achieved by first designing an opamp with moderate performance based on symmetric voltage distribution and then modifying the node potentials to meet the target specifications. A fully differential telescopic opamp along with common mode feedback circuit is thus designed using PDM and the simulation results are presented.