Rejection of Power Supply Noise in Wheatstone Bridges : Application to Piezoresistive MEMS

TL;DR

This paper presents a feedback-based architecture for Wheatstone bridges in piezoresistive MEMS to effectively reject power supply noise and offset, enhancing sensor resolution.

Contribution

It introduces a feedback control method to compensate resistor mismatches in Wheatstone bridges, improving noise rejection and sensor resolution.

Findings

Enhanced offset cancellation with feedback control

Improved resolution in piezoresistive MEMS sensors

Effective rejection of power supply noise

Abstract

This paper deals with the design of MEMS using piezoresistivity as transduction principle. It is demonstrated that when the sensor topology doesn't allow a perfect matching of strain gauges, the resolution is limited by the ability of the conditioning circuit (typically a Wheatstone bridge) to reject power supply noise. As this ability is strongly reduced when an offset voltage is present at the output of the bridge, the proposed architecture implements a feedback loop to control MOS transistors inserted in the Wheatstone bridge to compensate resistor mismatches. This feedback exhibits a very good offset cancellation and therefore a better resolution is achieved.