A 7.4 μW Temperature Detecting Circuit for Battery Monitoring System

A low-power and high-precision temperature detecting circuit consisting of a temperature sensing circuit and an incremental delta-sigma (Delta Sigma) analog-to-digital converter (ADC) is designed in this paper. A simple temperature sensing circuit with a bipolar transistor, several current mirror transistors and a source follower is proposed to sense temperature information. The base-emitter voltage with a wide voltage range is proposed to adapt for input of ADC, which significantly reduce the design requirement of ADC. The incremental delta-sigma modulator adopting 1-bit, 2nd-order, and CIFF structure achieves high linearity and high precision in this study. The whole circuit is successfully implemented in a 0.18 mu m standard CMOS process. Simulation results show that the proposed temperature detecting circuit with a total power consumption of 7.4 mu W achieves a resolution of 0.04. and good linearity.