High Slew Rate Current Feedback Amplifier

Abstract

Two internally compensated CMOS currentfeedback operational amplifiers are implemenated. The higher speed exhibited by the Current-feedback OpAmp, compared to conventional architectures, is mainly due to the superior slew-rate, whereas the constant closed-loop bandwidth relies on a low input resistance value. The circuits are entirely made up of class AB stages, thereby increasing slew rate and drive capability, avoiding many of the drawbacks incurred by previous CMOS and even bipolar implementations. Experimental results on one prototype fabricated in a 0.35- m process using a 20-pF load and supplied with 3.3 V are also given, showing, as main performance parameters,a SR of >400 V/μs.