title: A Novel Digital Closed Loop MEMS Accelerometer Utilizing a Charge Pump.
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.
authors.affiliation: Department of Precision Instrument, Tsinghua University, Beijing 100084, China. chuyx11@mails.tsinghua.edu.cn.
authors.forename: Yixing
authors.initials: Y
authors.lastname: Chu
authors.affiliation: Department of Precision Instrument, Tsinghua University, Beijing 100084, China. dongjx@mail.tsinghua.edu.cn.
authors.forename: Jingxin
authors.initials: J
authors.lastname: Dong
authors.affiliation: Institute of Microelectronics, Tsinghua University, Beijing 100084, China. chibylxc@tsinghua.edu.cn.
authors.forename: Baoyong
authors.initials: B
authors.lastname: Chi
authors.affiliation: Department of Precision Instrument, Tsinghua University, Beijing 100084, China. yfliu@mail.tsinghua.edu.cn.
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Liu
keywords: MEMS accelerometer; charge pump; closed loop; sigma delta modulator