High-order electromechanical /spl Sigma//spl Delta/ modulation in micromachined inertial sensors

Analysis of second-order electromechanical sigma-delta (/spl Sigma//spl Delta/) inertial sensors shows that in-band quantization error introduces a resolution penalty, which cannot be eliminated by oversampling. In addition, a tradeoff between resolution and phase compensation forces such systems to operate with reduced phase margin. This paper introduces high-order electromechanical /spl Sigma//spl Delta/ modulation as an approach, which eliminates the quantization noise overhead and allows for increased phase compensation without degrading the resolution. Quasi-linear analysis is used to evaluate the contribution of the individual noise sources to the output of the system and to examine the effect of noise interaction on the behavior of electromechanical /spl Sigma//spl Delta/ modulators.

[1]  Gene F. Franklin,et al.  Feedback Control of Dynamic Systems , 1986 .

[2]  B. Boser,et al.  A monolithic surface micromachined accelerometer with digital output , 1995 .

[3]  Weiping Li,et al.  Applied Nonlinear Control , 1991 .

[4]  B. Boser,et al.  A monolithic surface micromachined Z-axis gyroscope with digital output , 2000, 2000 Symposium on VLSI Circuits. Digest of Technical Papers (Cat. No.00CH37103).

[5]  G. Fedder,et al.  A low-noise low-offset chopper-stabilized capacitive-readout amplifier for CMOS MEMS accelerometers , 2002, 2002 IEEE International Solid-State Circuits Conference. Digest of Technical Papers (Cat. No.02CH37315).

[6]  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.

[7]  J.H. Smith,et al.  A 3-axis surface micromachined /spl Sigma//spl Delta/ accelerometer , 1997, 1997 IEEE International Solids-State Circuits Conference. Digest of Technical Papers.

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

[9]  John J. Paulos,et al.  An analysis of nonlinear behavior in delta-sigma modulators , 1987 .

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