Effects of MOSFET mismatch on the performance of single supply low voltage operational amplifiers

Abstract

Purpose

In this paper, we study the effect on the performance of a single supply low voltage operational amplifier due to such a mismatch.

Design/methodology/approach

We start with a given set of specifications and design a MOSFET based operational amplifier meeting those specifications. We then compute various parameters of the operational amplifier using PSPICE to verify that the amplifier meets the specifications. We create mismatch in three characteristics of differential pair MOSFETs: zero biased threshold voltage (V_th0), channel length (L) and process transconductance parameter (K). The effect of the mismatch on two performance parameters: (a) differential mode gain and (b) output DC voltage is then studied.

Findings

The effects of mismatch in MOSFET characteristics on the performance of single supply low voltage operational amplifiers are studied. Circuit designers can use the results to design operational amplifiers and other analog circuits to minimize the effects of such a mismatch on the performance of their circuits. In some cases, such a mismatch may even be desirable to obtain a desired performance from the circuit.

Practical implications

Circuit designers can use the results to design operational amplifiers and other analog circuits to minimize the effects of such a mismatch on the performance of their circuits.

Originality/value

Effect of mismatch of the transistor characteristics on the performance of circuits rarely reported in literature. This study is presented to aid circuit designers in designing circuits with enhanced performance.

Citation

Ramakrishnan, R. and Chaudhry, M.A. (2005), "Effects of MOSFET mismatch on the performance of single supply low voltage operational amplifiers", Microelectronics International, Vol. 22 No. 3, pp. 34-38. https://doi.org/10.1108/13565360510610521