Simplified Design Methods for Operational Amplifiers

Author(s):

N.Sunarthy , New Horizon College of Engineering, Bangalore; Monika Gupta, New Horizon College of Engineering, Bangalore

Keywords:

PDM; Op-amp; Bias Conditions; Transistor Sizing

Abstract:

This paper describes a simplified design method for fully differential folded cascode amplifier using Potential Distribution Method (PDM). Designers often spend more time in designing op-amps analytically, and then realize that the simulated circuits do not match analytical expectations. This complexity is due to modeling of short channel MOS devices using long channel equations. Finally, a design method is adopted to realize the op-amp with the help of a simulator. Proposed Potential Distribution Method is a design methodology based on actual behavior of the devices and it is free from any analytical expression. PDM is based on simulator results obtained with pre-defined bias conditions. Based on the performance parameters like unity gain bandwidth, slew rate, phase margin etc., the current and voltage distribution at different nodes is presented and using these dependencies the target specifications for an op-amp can be achieved with shorter design time. This method guarantees that all transistors operate at saturation region. This technique is independent of the process technology and device length. Thus a simple method to determine the aspect ratio.

Other Details:

Manuscript Id	:	IJSTEV2I12229
Published in	:	Volume : 2, Issue : 12
Publication Date	:	01/07/2016
Page(s)	:	640-643

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