A Temperature Coefficient Amplified Temperature Sensor

Abstract

Thermal sensing stands as an essential functionality in Internet of Things (IoT) devices, serving to monitor environmental or intrinsic system chip conditions. High resolution in temperature measurement typically necessitates the employment of high resolution Analog-to-Digital Converters (ADCs) with resourceful power consumed calibrated, a requirement that impedes their integration in ultra-low-power sensor nodes. This research introduces a low-power temperature sensor design that incorporates a temperature coefficient amplifier. The innovative aspect of this amplifier is its generation of a negative PTAT voltage, facilitating an enhanced gradient of both PTAT and CTAT voltages, reaching approximately 10mV/°C across a temperature span of -30°C to 110°C. Constructed using 180 nm CMOS technology, the sensor occupies an area of 0.22 mm². Simulation results reveal that the sensor attains a resolution of 42mK and consumes 0.572 nJ per conversion, achieving a Figure of Merit of 1.009 pJK². By employing a split CDAC, the sensor efficiently samples leakage-based current within 20ms, enabling its conversion into digital code.