@conference {Graaf2004Quadrature-osci, title = {Quadrature oscillator with pre-distorted waveforms for application in MEMS-based mechanical spectrum analyser}, booktitle = {Solid-State Circuits Conference, 2004. ESSCIRC 2004. Proceeding of the 30th European}, year = {2004}, month = {sep.}, pages = {407 - 410}, abstract = {An AC-operated capacitive accelerometer with electrostatic force feedback is employed for direct mechanical spectrum analysis. A suitable electrostatic AC field is used to make the accelerometer selectively sensitive to only the coherent mechanical frequency component. By sweeping the frequency of the drive voltage over a selected range, the mechanical (vibration) spectrum is analysed in the mechanical domain. Operation requires the simultaneous generation of predistorted sine- and cosine-like waveforms. A DDFS with DAC, based on a specially scaled resistive string, is designed, fabricated in CMOS and tested. Spurious free dynamic range is 22 dB over a frequency range of DC up to 1 kHz. The spectral performance is comparable to FFT-based systems for spectral analysis on a time series supplied by a conventional accelerometer, while the overall system features a reduced complexity, simple spectral in-zooming and potential for low power consumption.}, keywords = {0 Hz to 1 kHz, AC-operated capacitive accelerometer, accelerometers, capacitive sensors, CMOS, CMOS integrated circuits, cosine-like waveforms, DAC, DDFS, digital-analogue conversion, direct digital synthesis, direct mechanical spectrum analysis, drive voltage frequency sweeping, electrostatic AC field, electrostatic devices, electrostatic force feedback, MEMS-based mechanical spectrum analyser, micromachined capacitive accelerometer, microsensors, predistorted waveforms, quadrature oscillator, scaled resistive string, selectively sensitive accelerometer, sine-like waveforms, spectral analysers, spectral in-zooming, spurious free dynamic range, swept-frequency oscillators, vibration analysis, vibration measurement}, doi = {10.1109/ESSCIR.2004.1356704}, url = {http://dx.doi.org/10.1109/ESSCIR.2004.1356704}, author = {de Graaf, G. and Mol, L. and Rocha, L. and Cretu, E. and Wolffenbuttel, R. F.} }