A CMOS Smart Temperature Sensor With Single-Point Calibration Method for Clinical Use

A smart temperature sensor has been realized using a Taiwan Semiconductor Manufacturing Company (TSMC) 0.18-μm standard CMOS process. Substrate positive-negative- positive (PNP) transistors are used to extract the temperature information. Using the techniques of dynamic element matching, single-transistor approach, and offset cancellation, the process spread between batches on the transistors becomes the main inaccuracy sources of the temperature sensor. The sensor uses a single-point calibration method that reduces the process spread and simplifies trimming. The temperature sensor can realize an inaccuracy (±3δ) within ±0.1°C in the temperature range from 20°C to 50°C after singlepoint calibration. The average power consumption of the sensor is 16 μW at the conversion rate of 10 Hz. These properties allow the use of the temperature sensor in clinical electronic thermometers.