Browsing by Author "Ünlügedik, A."

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Designing transmitting CMUT cells for airborne applications
    (Institute of Electrical and Electronics Engineers Inc., 2014) Ünlügedik, A.; Taşdelen, A.; Atalar, Abdullah; Köymen, Hayrettin
    We report a new mode of airborne operation for capacitive micromachined ultrasonic transducers (CMUT), in which the plate motion spans the entire gap without collapsing and the transducer is driven by a sinusoidal voltage without a dc bias. We present equivalent-circuit-based design fundamentals for an airborne CMUT cell and verify the design targets using fabricated CMUTs. The performance limits for silicon plates are derived. We experimentally obtain 78.9 dB//20 μPa@1 m source level at 73.7 kHz, with a CMUT cell of radius 2.05 mm driven by 71 V sinusoidal drive voltage at half the frequency. The measured quality factor is 120. We also study and discuss the interaction of the nonlinear transduction force and the nonlinearity of the plate compliance. © 1986-2012 IEEE.
  • Thumbnail Image
    ItemOpen Access
    Unbiased charged circular CMUT microphone: lumped-element modeling and performance
    (Institute of Electrical and Electronics Engineers, 2018) Köymen, Hayrettin; Atalar, Abdullah; Güler, S.; Köymen, I.; Taşdelen, A. S.; Ünlügedik, A.
    An energy-consistent lumped-element equivalent circuit model for charged circular capacitive micromachined ultrasonic transducer (CMUT) cell is derived and presented. It is analytically shown and experimentally verified that a series dc voltage source at the electrical terminals is sufficient to model the charging in CMUT. A model-based method for determining this potential from impedance measurements at low bias voltages is presented. The model is validated experimentally using an airborne CMUT, which resonates at 103 kHz. Impedance measurements, reception measurements at resonance and off-resonance, and the transient response of the CMUT are compared with the model predictions.