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Yayın Integrated ultrasonic imaging systems based on CMUT arrays: Recent progress(IEEE, 2004) Wygant, Ira O.; Zhuang, Xuefeng; Yeh, David T.; Nikoozadeh, Amin; Oralkan, Ömer; Ergün, Arif Sanlı; Karaman, Mustafa; Khuri-Yakub, Butrus ThomasThis paper describes the development of an ultrasonic imaging system based on a two-dimensional capacitive micromachined ultrasonic transducer (CMUT) array. The transducer array and front-end electronics are designed to fit in a 5-mm endoscopic channel. A custom-designed integrated circuit, which comprises the front-end electronics, will be connected with the transducer elements via through-wafer interconnects and flip-chip bonding. FPGA-based signal-processing hardware will provide real-time three-dimensional imaging. The imaging system is being developed to demonstrate a means of integrating the front-end electronics with the transducer array and to provide a clinically useful technology. Integration of the electronics can improve signal-to-noise ratio, reduce the number of cables connecting the imaging probe to a separate processing unit, and provide a means of connecting electronics to large two-dimensional transducer arrays. This paper describes the imaging system architecture and the progress we have made on implementing each of its components: a 16×16 CMUT array, custom-designed integrated circuits, a flip-chip bonding technique, and signal-processing hardware.Yayın Design of a front-end integrated circuit for 3D acoustic imaging using 2D CMUT arrays(IEEE-INST Electrical Electronics Engineers Inc, 2005-12) Çiçek, İhsan; Bozkurt, Ayhan; Karaman, MustafaIntegration of front-end electronics with 2D capacitive micromachined ultrasonic transducer (CMUT) arrays has been a challenging issue due to the small element size and large channel count. We present design and verification of a front-end drive-readout integrated circuit for 3D ultrasonic imaging using 2D CMUT arrays. The circuit cell dedicated to a single CMUT array element consists of a high-voltage pulser and a low-noise readout amplifier. To analyze the circuit cell together with the CMUT element, we developed an electrical CMUT model with parameters derived through finite element analysis, and performed both the pre- and postlayout verification. An experimental chip consisting of 4 x 4 array of the designed circuit cells, each cell occupying a 200 x 200 mu m(2) area, was formed for the initial test studies and scheduled for fabrication in 0.8 mu m, 50 V CMOS technology. The designed circuit is suitable for integration with CMUT arrays through flip-chip bonding and the CMUT-on-CMOS process.Yayın Üç boyutlu akustik görüntüleme için ön alıcı-verici tümdevre(IEEE, 2004) Çiçek, İhsan; Bozkurt, Ayhan; Karaman, MustafaTıbbi ultrasonik görüntüleme sistemleri, genel olarak bir çevirici elemanı ve akustik işaretin üretilip algılanmasından sorumlu elektronik oluşmaktadır. Tek boyutlu dönüştürücü dizileriyle, incelenmekte olan ortamın iki boyutlu kesit görüntüsü elde edilmektedir. Dönüştürücü teknolojisindeki son gelişmelerle, iki boyutlu dönüştürücü dizilerinin üretimi gerçekleştirilmiş, böylece üç boyutlu (hacimsel) görüntüleme yapılması mümkün olmuştur[1,2]. Ancak, özellikle Nyquist kriteri, dönüştürücü elemanların boyutlarını sınırladığı için, eleman boyutları oldukça küçülmüştür; bu da algılanan işareti oldukça zayıflatmaktadır. Bu nedenle, kabul edilebilir nitelikteki görüntülerin alınabilmesi için, alıcı-verici elektroniğinin iyileştirilmesi gerekmektedir. Bu çalışmada, iki boyutlu akustik çeviriciler için CMOS tabanlı ön alıcı-verici devresinin tasarımı gerçekleştirilmiştir. Devre, temel olarak, bir yüksek gerilim darbe üretici, alıcı-verici anahtarı, düşük gürültülü ön yükseltici ve dönüştürücü elemanın bağlantı dolgulamasından oluşmaktadır.Yayın An integrated circuit with transmit beamforming and parallel receive channels for real-time three-dimensional ultrasound imaging(IEEE, 2006) Wygant, Ira O.; Lee, Hyunjoo J.; Nikoozadeh, Amin; Yeh, David T.; Oralkan, Ömer; Karaman, Mustafa; Khuri-Yakub, Butrus ThomasWe present the design of an integrated circuit (IC) that will be flip-chip bonded to a 16 x 16-element CMUT array. The IC provides 16 receive channels which can be configured to receive along either of the array diagonals or on any single row of the array. On transmit, all 256 elements can be used to transmit arbitrarily focused beams. Focused transmission with the full array is made possible by on-chip pulsers and memory. A 25-V pulser and 8-bit shift register is provided for each element of the array. Prior to each transmit, new values are loaded into the shift registers. Current-con trolled one-shots control the transmit pulse widths. Circuit simulations and the IC layout are presented. Simulations predict that delay values can be loaded in less than 1.3 mu s and show the generation of precisely timed pulses. The IC is being prepared for submission to National Semiconductor for fabrication in a high-voltage BiCMOS process.
