Optimization of a Collapsed Mode CMUT Receiver for Maximum Off-Resonance Sensitivity
JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, cilt.27, sa.5, ss.921-930, 2018 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 27 Sayı: 5
- Basım Tarihi: 2018
- Doi Numarası: 10.1109/jmems.2018.2857444
- Dergi Adı: JOURNAL OF MICROELECTROMECHANICAL SYSTEMS
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
- Sayfa Sayıları: ss.921-930
- Yıldız Teknik Üniversitesi Adresli: Evet
Özet
We propose an airborne collapse capacitive micromachined ultrasonic transducer (CMUT) as a practical viable ultrasound transducer capable of providing a stable performance at the off-resonance frequencies. Traditional practice is to bias the CMUT plate close to collapse voltage to achieve high coupling coefficient and sense the incoming ultrasound as an open-circuit receive voltage signal of the transducer or short-circuit receive current (SCRC). Maintaining CMUT plate in the vicinity of collapse threshold is rather difficult. In this paper, an analytic approach to design an airborne collapsed-mode CMUT for maximum off-resonance sensitivity is presented. We use small-signal circuit model to evaluate the performance of a collapsed CMUT for varying operating conditions. CMUT operational parameters that yield the highest off-resonance SCRC are directly obtained from performance design curves. Collapsed CMUT plate is then biased in a critical biasing region that produces a stable and maximum off-resonance sensitivi ty. We experimentally verify and measure a stable sensitivity of a fabricated collapsed CMUT cell of -60 dB V/Pa at 100 kHz when biased between 50 to 65 V. We characterize our linear circuit model performance against the measured performance of collapsed CMUT in air within 4-dB tolerance.