Tutorial: Low-Noise Current Sensing

Low-noise current readouts are indispensable components in modern electronics, facilitating accurate measurement of tiny currents with the highest possible signalto-noise ratio. They find applications in various fields, including sensor interfaces, medical devices, and environmental monitoring systems. In this tutorial, after a short motivation including some example applications and specifications, we review the basics of resistive and capacitive feedback transimpedance amplifiers, including the relevant feedback theory. We then discuss more recent implementations, including low-noise current-input σΔ modulators, current conveyors, and current-to-frequency converters before we conclude the tutorial with a brief summary, highlighting relevant work at ISSCC 2025.