A2.1-ppm/°C current-mode CMOS bandgap reference with piecewise curvature compensation

This paper presents a high-precision, low temperature coefficient (TC) CMOS bandgap reference for high-performance multi-channel ADC working under wide temperature range. A piecewise curvature compensation technique is proposed to extend its operating temperature range and keep its low temperature coefficient. A β-compensation technique is used to cancel the PTAT and non-PTAT spread of the output due to variation of β in the BJTs. Moreover, the trimming resistors are implemented to calibrate the 1st-order temperature coefficient and absolute value of the output voltage. The bandgap reference designed in 0.18μm CMOS process has a super low temperature coefficient of 2.1ppm/°C over a wide temperature of -55°C to 140°C, making it appropriate to provide reference voltage for a high-precision ADC.