A ±5 A Integrated Current-Sensing System With ±0.3% Gain Error and 16 μA Offset From-55 °C to+85 °C

This paper presents an integrated current-sensing system (CSS) that is intended for the use in battery-powered devices. It consists of a 10 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 m CMOS process, occupies 1.15 mm(2) and draws 55 mu 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 degrees C to +85 degrees C, they exhibit a maximum offset of 16 mu A and a maximum gain error of +/- 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.