User login

Measuring and interpreting the mechanical-thermal noise spectrum in a MEMS

Publication Type:

Journal Article


(IOP) Journal of Micromechanics and Microengineering, Volume 15, Number 7, p.S30-S38 (2005)



Measuring and interpreting the mechanical_thermal noise spectrum in

L A Rocha et al 2005 J. Micromech. Microeng. 15 S30-S38 doi:10.1088/0960-1317/15/7/005

PDF (525 KB) | References

L A Rocha1, E Cretu2 and R F Wolffenbuttel1

1 Department for Microelectronics, Faculty of EEMCS, Delft University
of Technology, Mekelweg 4, 2628 CD Delft, The Netherlands

2 Melexis, Transportstr. 1, Tessenderlo, Belgium

Abstract. The meta-stability of the pull-in displacement of an electrostatically
operated parallel plate micromechanical structure is used for the
capacitive measurement of the mechanical_thermal noise spectrum in
a MEMS. Pull-in time depends on force and is not affected by the
input-referred noise of the readout circuit. Repeatedly bringing
the microstructure to pull-in while measuring the pull-in time followed
by FFT enables the measurement of the mechanical noise spectrum with
a non-mechanical noise level set primarily by the resolution of the
time measurement. The white noise level is found to be in agreement
with the theory on damping. The 1/f noise spectrum is found to be
independent of ambient gas pressure with a 1/f noise_white noise
cross-over frequency at 0.007 Hz for a 1 bar gas pressure and is
reproducible for devices fabricated in the same process and the same

Print publication: Issue 7 (July 2005)

Received 26 November 2004, in final form 28 February 2005

Published 20 June 2005