Design of Low Power Temperature Sensor Based on 180 nm Complementary Metal Oxide Semiconductor Technology

Abstract

CMOS temperature sensor is widely used in power monitoring system, power consumption is an important index. The digital filter power consumption is one of the main sources of the temperature sensor power consumption, and limiting the Digital filter power consumption becomes an important method to realize the low power consumption of the temperature sensor. Based on this, a low power digital filter for CMOS temperature sensors is designed, and a precision adaptive digital filter is proposed, the filter is cascaded by a recursive CIC filter and a FIR filter based on a shift adder, the order of CIC filter and FIR filter can be adjusted according to the difference between the measured temperature and the threshold temperature range set by the user, when the measured temperature is outside the threshold temperature range, the operation unit in the filter is selectively switched off, which makes the power consumption of the filter decrease. For the temperature range that does not need to be monitored, the requirement of temperature measurement accuracy is usually not high, if high-precision temperature monitoring is still carried out, it will have a lot of unnecessary power consumption, in this paper, an adaptive precision digital filter is used to solve the problem. In order to further reduce the power consumption of the temperature sensor, according to the characteristics of the slow change of the temperature signal, a single temperature conversion combined with idle off mode is adopted, the FIR filter power consumption is reduced by 5.5% by optimizing the single temperature conversion operation. The temperature sensor is realized by 180 nm CMOS process. The results show that the sensor can achieve an accuracy of 0.47 °C in the temperature range of −55–115 °C when the measured temperature is in the threshold temperature range, under 1.8 V supply voltage, the power consumption of the digital part of the sensor is 20.15 μw. When the measured temperature is outside the threshold temperature range, the power consumption of the digital part of the sensor can be reduced by 11.3%.