Fast settling GaAs operational amplifiers for switched capacitor applications

Consideration is given to fast-settling high-gain GaAs operational amplifiers for high-frequency switched-capacitor-filter applications. A previous amplifier with a gain of 60 dB is critically assessed from the point of view of settling time, and the device geometry is altered to reduce settling time from 450 ps to a minimum of 360 ps. General circuit techniques for obtaining faster settling are developed, leading to two designs which have gains still exceeding 60 dB but with minimum settling times now approaching 200 ps