A feedforward compensation scheme for high gain wideband amplifiers

摘要

A No-Capacitor FeedForward (NCFF) compensation which uses pole-zero cancellation to obtain high gain, high GBW and a good phase margin is proposed. Left half plane (LHP) zeros produced due to the feedforward path cause a +90/spl deg/ shift in the phase and are used to cancel the -90/spl deg/ shifts in the phase caused by the poles. A fully differential OTA using the NCFF compensation scheme has been designed using AMI 0.5 /spl mu/m technology; DC gain of 97 dB, GBW of 325 MHz, settling time of 5 ns and phase margin of around 90/spl deg/ are achieved.