Very low-voltage fully differential amplifier for switched-capacitor applications

A fully differential opamp suitable for very-low voltage switched-capacitor circuits in standard CMOS technologies is introduced. The proposed two stage opamp needs a simple low voltage CMFB switched-capacitor circuit only for the second stage. Due to the reduced supply voltage, the CMFB circuit is implemented using boot-strapped switches. Minor modifications allow to use chopper stabilization for flicker noise reduction. Two different compensation schemes are discussed and compared using an example for 1 V operation of the amplifier.