A Wide Range, Energy-Efficient Temperature Sensor Based on Direct Temperature-Voltage Comparison

Abstract

This letter presents a successive-approximation register (SAR) temperature sensor using a clocked temperature-voltage comparator. The clocked comparator is designed to have a PTAT input offset voltage, which is quantized by SAR. Temperature transduction is spatially and temporally confined in the comparator's dynamic comparison. Other circuit operations are robust to the temperature changes so that the sensor's measurement range can be maximized. Also, the sensor inherits many good aspects of an SAR ADC, such as simple design and operation, no need for complex digital filtering, and low energy consumption. As a result, the test chip fabricated in a 0.18-mu m CMOS process shows a wide temperature sensing range of -50 degrees C to +130 degrees C, with a low energy consumption of 38.69 pJ/conv. After two-point calibration, the temperature sensor shows a 3-sigma temperature inaccuracy of -2.54.degrees C/+2.16 degrees C.