A CMOS MEMS Thermal Sensor with High Frequency Output

Abstract — This work presents the design and characterization of a CMOS-integrated thermal sensor that features a novel oscillator-based sensing interface to achieve a high thermoelectric sensitivity. The thirty pairs of thermocouples are made of n+/p+ polysilicon of a standard 0.18-μm CMOS to produce a large thermoelectric voltage. The produced thermoelectric voltage is used to control the bias current of a high-frequency oscillator circuit and causes a shift in the output frequency. Experimental result indicates the 544-MHz oscillator has a temperature sensitivity of 46.3 kHz/°C. I