A low noise and low temperature coefficient CMOS bandgap reference for MEMS micro-accelerometer

Abstract

A voltage reference with low noise and low temperature coefficient, applicable to accelerometers, was presented based on the analysis of conventional bandgap reference (BGR) in this paper. A chopper stabilized technique, which modulated the low frequency noise and offset components to higher frequencies by a mixing operation followed by filtering low-pass filtering, served effectively to reduce the low frequency noise and offset components of the proposed reference voltage circuit. To achieve a low temperature coefficient over a broad temperature range, a high-order curvature compensation technique, which used a temperature dependent resistor ratio generated by a high poly resistor and a nwell resistor, was introduced. The proposed circuitry was designed in standard 2.0µm CMOS process. The simulation results showed that the output noise spectral density was 169.68nV/Hz1/2 ranging from 1Hz to 10kHz when chopping frequency was high enough to ignore the low frequency 1/f noise. The average temperature coefficient was 6.25ppm/D in the temperature range from −40 to 80 D.