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

In industrial control systems, high-voltage instrumentation amplifiers (HV-IAs) are employed to process millivolt-level signals from sensors and standardized 4-to-20mA current signals from transmitters [1], [2]. The latter are converted into voltage signals up to 10V via a $250\Omega$ or $500\Omega$ resistor before being processed by the HV-IA [3]. Therefore, gain-adjustable IAs with a large differential input range $(> 20\mathrm{V}_{\text{pp}})$ are required. Due to common-mode (CM) interference and varying ground potentials, input signals can exhibit substantial CM components up to $\pm 10\mathrm{V}$ Jnecessitating a large CM input range and common-mode rejection-ratio (CMRR) of more than 120dB. Additionally, high input impedance $(> 10\mathrm{M}\Omega)$ [1] is essential for handling signal sources with weak driving capability, while the closed-loop architecture constrains the bandwidth at high-gain settings. These make energy-efficient capacitively-coupled IAs [4], [5] less preferable.