Noise analysis and characterization of a sigma-delta capacitive microaccelerometer

Haluk Külah, Junseok Chae, Navid Yazdi, Khalil Najafi

Research output: Contribution to journalArticlepeer-review

195 Scopus citations


This paper reports a high-sensitivity low-noise capacitive accelerometer system with one micro-g/√Hz resolution. The accelerometer and interface electronics together operate as a second-order electromechanical sigma-delta modulator. A detailed noise analysis of electromechanical sigma-delta capacitive accelerometers with a final goal of achieving sub-μg resolution is also presented. The analysis and test results have shown that amplifier thermal and sensor charging reference voltage noises are dominant in open-loop mode of operation. For closed-loop mode of operation, mass-residual motion is the dominant noise source at low sampling frequencies. By increasing the sampling frequency, both open-loop and closed-loop overall noise can be reduced significantly. The interface circuit has more than 120 dB dynamic range and can resolve better than 10 aF. The complete module operates from a single 5-V supply and has a measured sensitivity of 960 mV/g with a noise floor of 1.08 Mg/√Hz in open-loop. This system can resolve better than 10 μg/√Hz in closed-loop.

Original languageEnglish (US)
Pages (from-to)352-360
Number of pages9
JournalIEEE Journal of Solid-State Circuits
Issue number2
StatePublished - Feb 2006


  • Capacitive readout
  • Inertial sensors
  • Micro-g
  • Microaccelerometers
  • Sigma-delta
  • Switched capacitor

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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