A High-precision CMOS Temperature Sensor

In this paper, a high-precision temperature sensor designed by a standard 0.18 mu m CMOS process with 3.3-V power supply is presented. The CMOS temperature sensor mainly consists of a bandgap reference (BGR) circuit and a SAR ADC circuit. In the BGR circuit, not only the traditional first-order compensation technique is adopted, but also a high-order curvature correction technique is used to obtain two accurate reference voltages, which are adopted as reference voltages for the SAR ADC, and a twice emitter-base voltage of BJT is used as a temperature sensing voltage for the SAR ADC. Simulation results show that temperature coefficients of two reference voltages are as low as 1.16 ppm/degrees C and 3.66 ppm/degrees C over a temperature range of 165 degrees C (-40 degrees C to 125 degrees C), PSRRs are up to -100 dB at low frequency. The CMOS temperature sensor achieves 0.1 degrees C temperature resolution, and +/- 0.35 degrees C absolute accuracy.