Computer evaluation of differential amplifier performance

A computational technique for determination of the important figures of merit of differential amplifiers is proposed. The method evolves from a reformulation of the transfer characteristics of differential amplifiers to clearly define the dc and ac performance of the amplifier. With this reformulation, ideal differential amplifier performance can be precisely defined, and expressions for the important transfer gains, common-mode rejection ratio, and dc offset voltages can be derived in terms of the differential-mode and common-mode gains and component mismatches. These expressions are easily implemented in a computer simulation package. The usefulness of the technique is illustrated by example.