A 366kS/s 400uW 0.0013mm2 frequency-to-digital converter based CMOS temperature sensor utilizing multiphase clock

The proposed temperature sensor is based on CMOS ring oscillators and a frequency-to-digital converter capable of simple and efficient temperature conversion to digital value. The proposed temperature sensor consumes 400 uW at a conversion rate of 366 kS/s and performs the fastest temperature-to-digital conversion among those introduced in previous work. The whole block occupies 0.0066 mm² (0.0013 mm² for temperature sensor). Four multiphase clocks were utilized to enhance the resolution of the sensor 8 times better. After one point calibration, the chip-tochip measurement spread was +2.748degC ~ -2.899degC over the temperature range of -40degC to 110degC.