A capacitively-coupled chopper operational amplifier with 3μV Offset and outside-the-rail capability

This paper presents a capacitively-coupled chopper operational amplifier whose maximum input common-mode voltage far exceeds its 5V supply. To achieve low offset, it employs a capacitively-driven input chopper, which can handle the wide input common-mode voltage with low power dissipation. To suppress chopping ripple, it employs an area-efficient switched-capacitor ripple-reduction loop. Implemented in a high-voltage 0.7μm CMOS technology, the amplifier achieves 3μV offset and an NEF of 5.1, while consuming 10μA. The chip has an active area of 1.2mm².