Analog Frontend for Reliable Human Body Temperature Measurement for IoT Devices

In this paper an analog frontend for a reliable measurement of the human body temperature is presented. A new and novel temperature calibration technique using an on-chip resistor was developed specifically for the analog frontend. The discussed analog frontend consists of a bandgap current reference, a precision current source, a programmable gain amplifier, a voltage source proportional to absolute temperature and an on-chip calibration resistor. The developed calibration technique enables very high accuracy, even 0.1 °C, to be obtained in a very wide temperature range. This calibration method was elaborated for integrated circuits operating in temperatures from −40 °C to +125 °C. The presented analog frontend consumes no more than 185 μA and was designed and manufactured with United Microelectronics Corporation (UMC) CMOS 130 nm technology. The data presented in the paper were obtained from process corner and Monte Carlo simulations as well as from measurements. The measurements were taken using a manual wafer prober with climate-controlled microchamber, at temperatures ranging from −40 °C to +125 °C.