Slewing investigation and improved design rules for SC circuits employing two-stage amplifiers with current-buffer Miller compensation

The Slewing behavior of two-stage operational amplifiers (op-amps) with current-buffer Miller compensation (CBMC) is examined. It is shown that the current buffer used in the compensation network significantly affects the Slewing characteristics of the amplifier in typical switched-capacitor (SC) applications. On the basis of the amplifier behavior investigation, improved early-design rules are suggested to overcome the limitation of the conventional approach that neglects the current buffer impact on the Slewing circuit performance. To demonstrate the validity of the proposed rules, a design example of a CBMC op-amp in a commercial 0.35 mum CMOS technology is also presented.