A Highly Integrated Radio Frequency Receiver RF CMOS Module for Core Body Temperature Thermometer

This paper presents a highly integrated radio frequency (RF) CMOS receiver module for monitoring the core body temperature thermometer, which operates in the dual band 1.35 and 2.75 GHz ranges. The RF receiver IC, such as a Dicke radiometer, includes the full receiver circuits, RF switch and modulator, and duty calibrating circuit using a 65 nm CMOS process. With the proposed duty cycle modulation, accurate temperature sensing is achievable even with a receiver gain mismatch and fluctuation. The measured temperature ranges from 22 to 47.3°C, and the measured voltage slope is 2.97 mV/ms • °C, and the temperature error is less than 0.9°C in 1.35 GHz band. The radiometric RF CMOS IC has a size of
$1.6\times2.3$
mm2 and the current consumption of 52 mW. Unlike the general skin temperature measurement of existing infrared (IR) sensors, the RF microwave core body thermometer equipped with an RF receiver IC that measures core body temperature inside a human body will be used in various fields as a digital healthcare and medical device.