Design procedures for a fully differential folded-cascode CMOS operational amplifier

Abstract

A fully differential folded-cascode op. amp. is analyzed, and the results are presented in the form of design equations and procedures. Tradeoffs among such factors as bandwidth, gain, phase margin, bias currents, signal swing, slew rate, and power are made evident. Closed-form expressions are developed, and a sequence of design steps is established. A graphical representation of the relationships among the gain, power, and phase margin for different capacitive loadings is presented to illustrate visually one form of design optimization. The results of SPICE simulations are shown to agree very well with the design equations presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>