A Near-Zero-Power Temperature Sensor with ±0.24 °c Inaccuracy Using only Standard CMOS Transistors for IoT Applications

We propose a near-zero-power temperature sensor only by using standard CMOS transistors without any resistor and special device or process. A pair of temperature sensing elements by employing the normal CMOS transistors is adopted to generate the proportional-to-absolute temperature (PTAT) and constant with temperature (CWT) sensing voltages. Then the two sensing voltages are converted to two reference current sources by using the proposed ultra-low-power voltage-to-current (VI) converter. The VI converter converts the linear voltage signal to an exponential current source with a constant exponent coefficient by using CMOS transistors instead of the conventional resistors. As a result, both power loss and chip area are saved. The whole temperature sensor is designed in standard 0.18 pm CMOS process with active area of only 0.017 mm². The supply voltage is 600 mV. After 1-point calibration, an accuracy of ±0.24 °C is achieved across the temperature range of 0 °C - 80 °C. The power consumption is only 22 pW for the sensing element, 25 pW for VI converter and 80 pW for total at room temperature (27 °C). The good performance and ultra-small facility of the temperature sensor shows its good practicality for Internet-of-Thing (IoT) applications.