A 32nV/√Hz Noise 13µV Offset 0~65V Input Common Mode Range Current Sensing Amplifier based on Switch Capacitor Circuit with 1~256 Gain

A current sensing amplifier with low noise, low offset and wide input common mode range (ICMR) is proposed in this paper. A Capacitively-Coupled Chopper Instrumentation Amplifier (CCIA) with high voltage (HV) chopper is used as the input stage to achieve $0 \sim 65\mathrm{V}$ ICMR. The switched-capacitor (SC) amplifier with correlated double sampling (CDS) technique is used as the driving stage to eliminate the offset of the input stage and provide the ADC driving capability. The proposed current sensing amplifier was simulated in 0.18um BCD process. The current sensing amplifier achieves $13 \mu \mathrm{V}$ input-referred offset, 32nV/$\surd$Hz input-referred noise, $1 \sim 256$ adjustable gain and 120dB CMRR at all gain settings within $0 \sim 65\mathrm{V}$ ICMR.