A Novel Digital Closed Loop MEMS Accelerometer Utilizing a Charge Pump.

Yixing Chu,Yunfeng Liu,Jingxin Dong,Baoyong Chi

doi:10.3390/s16030389

Abstract

This paper presents a novel digital closed loop microelectromechanical system (MEMS) accelerometer with the architecture and experimental evaluation. The complicated timing diagram or complex power supply in published articles are circumvented by using a charge pump system of adjustable output voltage fabricated in a 2P4M 0.35 µm complementary metal-oxide semiconductor (CMOS) process, therefore making it possible for interface circuits of MEMS accelerometers to be integrated on a single die on a large scale. The output bitstream of the sigma delta modulator is boosted by the charge pump system and then applied on the feedback comb fingers to form electrostatic forces so that the MEMS accelerometer can operate in a closed loop state. Test results agree with the theoretical formula nicely. The nonlinearity of the accelerometer within ±1 g is 0.222% and the long-term stability is about 774 µg.

Highlights

MEMS accelerometers are widely applied in numerous areas such as inertial navigation systems, smartphones, vehicle electronics, etc. [1,2]
Interface circuits for MEMS accelerometers are of great advantage because of their small size, low power dissipation, nice nonlinearity and low thermal drift [9,10,11,12,13]
The displacement of the proof mass is sensed by the readout circuit, and electrostatic forces are applied to keep the proof mass at its zero position

Summary

Introduction

MEMS accelerometers are widely applied in numerous areas such as inertial navigation systems, smartphones, vehicle electronics, etc. [1,2]. A novel digital closed loop method utilizing a charge pump [19,20,21], which can be realized, is proposed in this paper. This method makes it possible for interface circuits of MEMS accelerometers to be integrated on a single die on a large scale. It is effective for accelerometers of any range by adjusting the output of the charge pump correspondingly as well

MEMS Accelerometer Utilizing Charge Pump

Fabrication

Charge Pump System

Discussion

Charge pump:

Conclusions design experiments newMEMS