A capacitively coupled chopper instrumentation amplifier with a ±30V common-mode range, 160dB CMRR and 5μV offset

Abstract

This paper describes a capacitively coupled chopper instrumentation amplifier (CCIA) for current-sensing applications. A capacitively driven input chopper enables a ±30V input common-mode (CM) range and an input offset less than 5μV. The CCIA does not draw supply current from its input terminals or require a separate high-voltage (HV) supply; and has a common-mode rejection ratio (CMRR) in excess of 160dB, both of which represent significant improvements on the state-of-the-art [1-3]. Implemented in a HV CMOS 0.7μm technology, the CCIA achieves an NEF of 6.1 (6.5× better than [1-3]), while drawing only 26μA from a 3V supply.