Two-Stage Common-Mode Feedback Structures for Fully Differential Operational Amplifier
Deng Chun-jian · 2011
For different requirements of input and output stages in 2-stage fully differential operational amplifier(op-amp),continuous-time common-mode feedback circuit and switched-capacitor common-mode feedback(SC-CMFB) circuit were designed,which enlarged output swing while keeping DC voltage stable at normal operating point.Results from simulation based on 0.13 μm CMOS mixed-signal process showed that the continuous-time CMFB and SC-CMFB had a transient output of 1.06 mV and 2.21 mV,respectively,and the op-amp had a DC gain of 91.6 dB,a unity-gain frequency of 1.163 GHz with 1.5 pF load capacitance at 2.5 V.