A 4.5-mW Closed-Loop $\Delta\Sigma$ Micro-Gravity CMOS SOI Accelerometer

In this paper, design, implementation and characterization of a 3-V switched-capacitor (SC) DeltaSigma CMOS interface circuit for the closed-loop operation of a lateral capacitive micro-gravity silicon-on-insulator (SOI) accelerometer is presented. The interface circuit is based on a front-end programmable reference-capacitorless SC charge amplifier and a back-end second-order SC DeltaSigma modulator. The accelerometer is fabricated through a dry-release high aspect-ratio reduced-gap process. By incorporating the low-Q transfer function of the microaccelerometer in a feedback loop, the system's dynamic range is improved by 20 dB, leading to a measured resolution of 4 mug/radicHz and an output dynamic range of 95 dB at 20 Hz. The bias instability is 2 to 8 mug for 12 hours. The chip is fabricated in the 0.5-mum standard CMOS process with an area of 2.25 mm2. The integrated circuit (IC) consumes 4.5 mW of power

[1]  N. Yazdi,et al.  11. 6 A Multi-Step Electromechanical Σ∆ Converter for Micro-g Capacitive Accelerometers , 2003 .

[2]  B.V. Amini,et al.  A new input switching scheme for a capacitive micro-g accelerometer , 2004, 2004 Symposium on VLSI Circuits. Digest of Technical Papers (IEEE Cat. No.04CH37525).

[3]  Michael Kraft,et al.  A high-performance accelerometer with a fifth-order sigma–delta modulator , 2005 .

[4]  Bernhard E. Boser,et al.  17.6 A Fourth-Order Σ∆ Interface for Micromachined Inertial Sensors , 2004 .

[5]  N. Yazdi,et al.  A multi-step electromechanical /spl Sigma//spl Delta/ converter for micro-g capacitive accelerometers , 2003, 2003 IEEE International Solid-State Circuits Conference, 2003. Digest of Technical Papers. ISSCC..

[6]  F. Ayazi,et al.  A 2.5-V 14-bit /spl Sigma//spl Delta/ CMOS SOI capacitive accelerometer , 2004, IEEE Journal of Solid-State Circuits.

[7]  John Dorsey.  Continuous And Discrete Control Systems: Modeling, Identification, Design, And Implementation , 2001 .

[8]  T. Gabrielson.  Mechanical-thermal noise in micromachined acoustic and vibration sensors , 1993 .

[9]  Billie F. Spencer,et al.  Risk monitoring of buildings with wireless sensor networks , 2005 .

[10]  Jonathan J. Bernstein,et al.  Low-noise MEMS vibration sensor for geophysical applications , 1999 .

[11]  L. Richard Carley,et al.  Electromechanical /spl Delta//spl Sigma/ modulation with high-Q micromechanical accelerometers and pulse density modulated force feedback , 2006, IEEE Transactions on Circuits and Systems I: Regular Papers.

[12]  Bernhard E. Boser,et al.  A micromachined fully differential lateral accelerometer , 1996, Proceedings of Custom Integrated Circuits Conference.

[13]  F. Ayazi,et al.  A high resolution, stictionless, CMOS compatible SOI accelerometer with a low noise, low power, 0.25 /spl mu/m CMOS interface , 2004, 17th IEEE International Conference on Micro Electro Mechanical Systems. Maastricht MEMS 2004 Technical Digest.

[14]  F. Ayazi,et al.  Micro-gravity capacitive silicon-on-insulator accelerometers , 2005 .

[15]  R. Jacob Baker.  Cmos: Mixed-Signal Circuit Design , 2002 .

[16]  Farrokh Ayazi,et al.  A 2.5V 14-bit ΣΔ CMOS-SOI capacitive accelerometer , 2004 .

[17]  Gabor C. Temes,et al.  A noise-shaping accelerometer interface circuit for two-chip implementation , 2000, 2000 IEEE International Symposium on Circuits and Systems. Emerging Technologies for the 21st Century. Proceedings (IEEE Cat No.00CH36353).

[18]  F. Ayazi,et al.  Sub-micro-gravity capacitive SOI microaccelerometers , 2005, The 13th International Conference on Solid-State Sensors, Actuators and Microsystems, 2005. Digest of Technical Papers. TRANSDUCERS '05..

[19]  B.E. Boser,et al.  A fourth-order /spl Sigma//spl Delta/ interface for micromachined inertial sensors , 2004, IEEE Journal of Solid-State Circuits.

[20]  Bernhard E. Boser,et al.  A three-axis micromachined accelerometer with a CMOS position-sense interface and digital offset-trim electronics , 1999, IEEE J. Solid State Circuits.

[21]  F. Ayazi,et al.  Design optimization and implementation of a microgravity capacitive HARPSS accelerometer , 2006, IEEE Sensors Journal.

[22]  L. Carley,et al.  Electromechanical ΔΣ modulation with high-Q micromechanical accelerometers and pulse density modulated force feedback. , 2006 .

[23]  N. Yazdi,et al.  Precision readout circuits for capacitive microaccelerometers , 2004, Proceedings of IEEE Sensors, 2004..

[24]  C. Condemine,et al.  A 0.8 mA 50 Hz 15 b SNDR /spl Delta//spl Sigma/ closed-loop 10g accelerometer using an 8/sup th/-order digital compensator , 2005, ISSCC. 2005 IEEE International Digest of Technical Papers. Solid-State Circuits Conference, 2005..

[25]  R. Pintelon,et al.  On the equivalence of z-domain and s-domain models in system identification , 1996, Quality Measurement: The Indispensable Bridge between Theory and Reality (No Measurements? No Science! Joint Conference - 1996: IEEE Instrumentation and Measurement Technology Conference and IMEKO Tec.