A 36 V Current-Balancing Instrumentation Amplifier With ±24 V Input Range, 5.6 MHz BW, and 140 dB CMRR at All Gain Settings

This article presents a 36V high-voltage current-balancing instrumentation amplifier (HV-CBIA), providing a new solution for industrial signal-acquisition front ends, including PLC input modules and motor drivers, where large input range, wide bandwidth, and high common-mode rejection ratio (CMRR) are simultaneously required. The proposed HV-CBIA addresses these requirements through three innovations: 1) a class-AB transconductance (TC) stage with adaptive biasing is proposed to extend the differential-mode (DM) input range while minimizing quiescent current; 2) a source-input buffer is employed to enhance the driving capability of transimpedance (TI) stage, while a negative capacitance (NC) technique is further incorporated to nullify parasitic capacitance, thereby improving the bandwidth–efficiency trade-off; and 3) an HV chopper employing area-efficient HV switches is adopted to maintain high CMRR and low offset under significant common-mode (CM) and DM swings. Fabricated in a 0.18-$\mu $m BCD process, the proposed HV-CBIA achieves a ±24V DM input signal range, 5.6MHz bandwidth, and 140dB CMRR across all gain settings (0.4-50). It delivers a 280MHz gain–bandwidth product (GBW) at a gain of 50 while consuming only 0.7mA from an 8–36V supply, corresponding to a power efficiency of 400MHz/mA.