A BJT-Based CMOS Body Temperature Sensor Analog Front-End with Dynamic Element Matching

Abstract

This paper proposes a bipolar junction transistor (BJT) based complementary metal-oxide-semiconductor (CMOS) body temperature sensor analog front-end (AFE) with dynamic element matching (DEM). To reduce mismatches of current sources and transistors resulting from process spread, DEM is implemented. A chopper stabilization technique is implemented to minimize input offset at op-amp which forms a feedback loop to generate proportional-to-absolute-temperature (PTAT) currents in the temperature sensor core. The gain stage used to achieve high-resolution output of temperature sensor implements non-inverting amplifier using R-2R digital-to-analog converter (DAC) to perform amplification regardless of the output offset voltage of the temperature sensor core. The proposed temperature sensor is implemented in a $0.18 \mu\mathrm{m}$ CMOS process, occupies 0.1 mm2, and consumes $4.85 \mu\mathrm{A}$ from 3.3 V I/O and 1.8 V core voltage.