Mic-in-CMOS: CMUT as a Sealed-Gap Capacitive Microphone
IEEE International Ultrasonics Symposium (IEEE IUS), Nevada, Amerika Birleşik Devletleri, 7 - 11 Eylül 2020, (Tam Metin Bildiri)
- Yayın Türü: Bildiri / Tam Metin Bildiri
- Doi Numarası: 10.1109/ius46767.2020.9251557
- Basıldığı Şehir: Nevada
- Basıldığı Ülke: Amerika Birleşik Devletleri
- Yıldız Teknik Üniversitesi Adresli: Evet
Özet
The design and production of a CMOS compatible, watertight and ingress-proof CMUT (capacitive micromachined ultrasonic transducer) microphone, mic-in-CMOS, with vacuum-gap is described. We present an analytical model-based approach for the design of mic-in-CMOS, where a basis for quantitative comparison of performance trade-offs is provided. The sealed vacuum gap of the mic-in-CMOS is basically a lossless sensor, free of mechanical noise. Its SNR is determined by the noise of the pre-amplification electronics (the noise contributor in a CMUT with vacuum gap is essentially the radiation resistance, which is less than 0 dBA for audio band for a 1 mm(2) device). The design of mic-in-CMOS involves many multilateral trade-offs such as gap height vs membrane thickness vs sensitivity vs need for linear operation vs bias voltage and atmospheric depression, to name few. The mic-in-CMOS design can be mass produced using CMOS film stacks only, as such the fabrication process can be carried out entirely in a CMOS processes production line complemented with CMOS compatible post-processing approaches. Mic-in-CMOS has the advantage of low production cost with minimal packaging requirement and on-die EMI / EMC.