A A Integrated Current-Sensing System With % Gain Error and 16 μA Offset From to

Abstract

This paper presents an integrated current-sensing system (CSS) that is intended for the use in battery-powered devices. It consists of a $10\,\hbox{m}{\Omega} $ on-chip metal shunt resistor, a switched-capacitor (SC) $\Delta \Sigma $ ADC, and a dynamic bandgap reference (BGR) that provides the ADC’s reference voltage and also senses the shunt’s temperature. The CSS is realized in a standard $0.13\,\mu \text{m}$ CMOS process, occupies $1.15\,\text{mm}^2$ and draws $55\,\mu \text{A}$ from a 1.5 V supply. Extensive measurements were made on 24 devices, 12 of which were directly bonded to a printed-circuit board (PCB) and 12 of which were packaged in a standard HVQFN plastic package. For currents ranging from $-5 $ to $+ 5$ A and over a temperature range of $- 55^{\;\circ} {\text{C}}$ to $+ 85^{\;\circ} {\text{C}}$ , they exhibit a maximum offset of $16\;\mu \text{A}$ and a maximum gain error of $\pm 0.3\% $ . This level of accuracy represents a significant improvement on the state of the art, and was achieved by the use of an accurate shunt temperature compensation scheme, a low-leakage sampling scheme, and several dynamic error correction techniques.