Browsing by Author "Atalar, Abdullah"
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Bilateral CMUT cells and arrays: equivalent circuits, diffraction constants, and substrate impedance
Köymen, Hayrettin; Atalar, Abdullah; Taşdelen, A. S. (Institute of Electrical and Electronics Engineers Inc., 2017)We introduce the largesignal and smallsignal equivalent circuit models for a capacitive micromachined ultrasonic transducer (CMUT) cell, which has radiating plates on both sides. We present the diffraction coefficient ... 
BilRC: an execution triggered coarse grained reconfigurable architecture
Atak, O.; Atalar, Abdullah (IEEE, 201307)We present Bilkent reconfigurable computer (BilRC), a new coarsegrained reconfigurable architecture (CGRA) employing an executiontriggering mechanism. A control data flow graph language is presented for mapping the ... 
Binary sequences with low aperiodic autocorrelation for synchronization purposes
Kocabaş, Ş. E.; Atalar, Abdullah (IEEE, 2003)An evolutionary algorithm is used to find three sets of binary sequences of length 49100 suitable for the synchronization of digital communication systems. Optimization of the sets are done by taking into consideration ... 
Calculation of transformer ratio in mason's equivalent circuit for cMUTs
Ölçüm, Selim; Atalar, Abdullah; Köymen, Hayrettin; Şenlik, Muhammed Niyazi (IEEE, 2006)We present a new method to calculate the transformer ratio of a cMUT in Mason's Equivalent circuit model. The effect of the spring softening capacitance is also included in the analysis. We use the existing turns ratio ... 
Centimeter scale atomic force microscope imaging and lithography
Minne, S. C.; Adams, J. D.; Yaralioglu, G.; Manalis, S. R.; Atalar, Abdullah; Quate, C. F. (A I P Publishing LLC, 19980921)We present a 4 mm2 image taken with a parallel array of 10 cantilevers, an image spanning 6.4 mm taken with 32 cantilevers, and lithography over a 100 mm2 area using an array of 50 cantilevers. All of these results represent ... 
Characterization and imaging with lamb wave lens at gigahertz frequencies
Bozkurt, Ayhan; Yaralıoğlu, Göksenin; Atalar, Abdullah; Köymen, Hayrettin; Kramer, K. (IEEE, 19941011)Lamb wave lenses with conical refracting surfaces are fabricated for use at 400 MHz and 1 GHz. The conical surfaces are ground and polished with mechanical means and they are sufficiently smooth for the frequencies of ... 
Characterization of layered materials by the lamb wave lens
Atalar, Abdullah; Köymen, Hayrettin; Değertekin, F. Levent (IEEE, 1990)The Lamb wave lens is a type of lens that can replace the conventional lens of an acoustic microscope for some applications. When it insonifies a layered solid structure, it excites a single mode in the structure, provided ... 
Circuit theoretical method for efficient finite element analysis of acoustical problems
Ekinci, A. Suat; Atalar, Abdullah (IEEE, 1998)In the last decade, there has been an outstanding improvement in the computer aided design tools for VLSI circuits regarding solution times and the circuit complexity. This study proposes formulating the acoustic field ... 
Circuit theory based analysis of CMUT arrays with very large number of cells
Oguz, H. Kağan; Atalar, Abdullah; Köymen, Hayrettin (IEEE, 2013)We have recently developed a circuit theory based method to analyze large CMUT arrays and shown that mutual acoustic interactions significantly influence the transducer performance. We connect each cell in the array to a ... 
CMUT array element in deepcollapse mode
Olcum, Semih; Yamaner F.Y.; Bozkurt, A.; Köymen, Hayrettin; Atalar, Abdullah (IEEE, 2011)Collapse and deepcollapse mode of operations have boosted the pressure outputs of capacitive micromachined ultrasonic transducers (CMUTs) considerably. In this work, we demonstrate a CMUT element operating in the deepcollapse ... 
Compact and wideband CPW wilkinson power dividers for GaN MMIC applications
Sutbas, Batuhan; Özbay, Ekmel; Atalar, Abdullah (IEEE, 2018)This paper presents two types of modified CPW Wilkinson power dividers at Xband using GaN MMIC technology on a SiC substrate. Lumped element equivalents of the transmission line arms are used and they are capacitively ... 
Contact imaging in the atomic force microscope using a higher order flexural mode combined with a new sensor
Minne, S. C.; Manalis, S. R.; Atalar, Abdullah; Quate, C. F. (A I P Publishing LLC, 199601)Using an atomic force microscope (AFM) with a silicon cantilever partially covered with a layer of zinc oxide (ZnO), we have imaged in the constant force mode by employing the ZnO as both a sensor and actuator. The cantilever ... 
Deepcollapse operation of capacitive micromachined ultrasonic transducers
Olcum, S.; Yamaner F. Y.; Bozkurt, A.; Atalar, Abdullah (IEEE, 2011)Capacitive micromachined ultrasonic transducers (CMUTs) have been introduced as a promising technology for ultrasound imaging and therapeutic ultrasound applications which require high transmitted pressures for increased ... 
Design and implementation of a general purpose VLSI median filter unit and its applications
Karaman, Mustafa; Onural, Levent; Atalar, Abdullah (IEEE, 1989)A VLSI median filter unit has been designed and implemented in 3μ m M2 CMOS, using fullcustom VLSI design techniques. The unit consists of two singlechip median filters, one extensible and one realtime. The chips are ... 
Design and implementation of a generalpurpose median filter unit in CMOS VLSI
Karaman, M.; Onural, L.; Atalar, Abdullah (IEEE SolidState Circuits Society, 1990)A generalpurpose median filter unit configuration is proposed in the form of two singlechip median filters, one extensible and one realtime. The networks of the chips are pipelined and systolic at bit level and based ... 
Design and implementation of capacitive micromachined ultrasonic transducers for high power
Yamaner F.Y.; Ölçüm, Selim; Bozkurt, A.; Köymen, Hayrettin; Atalar, Abdullah (IEEE, 2011)Capacitive micromachined ultrasonic transducers (CMUTs) have a strong potential to compete piezoelectric transducers in high power applications. In a CMUT, obtaining high port pressure competes with high particle velocity: ... 
Design charts to maximize the gainbandwidth product of capacitive micromachined ultrasonic transducers
Ölçüm, Selim; Şenlik, Muhammed Niyazi; Bayram, Can; Atalar, Abdullah (IEEE, 2005)In this work we define a performance measure for capacitive micromachined ultrasonic transducers (cMUT) in the form of a gainbandwidth product to investigate the conditions that optimize the gain and bandwidth with respect ... 
Design considerations for MMIC distributed amplifiers
Ergun, Şanlı; Atalar, Abdullah (IEEE, 1994)The bandwidth of the input artificial line in a distributed amplifier is the main band limiting factor. By choosing this impedance properly the bandwidth of a distributed amplifier can be maximized. A four section GaAs ... 
Design of application specific processors for the cached FFT algorithm
Atak, Oğuzhan; Atalar, Abdullah; Arıkan, Erdal; Ishebabi, H.; Kammler, D.; Ascheid, G.; Meyr, H.; Nicola, M.; Masera, G. (IEEE, 200605)Orthogonal frequency division multiplexing (OFDM) is a data transmission technique which is used in wired and wireless digital communication systems. In this technique, fast Fourier transformation (FFT) and inverse FFT ... 
Designing an efficient wide bandwidth single cell CMUT for airborne applications using nonlinear effects
Unlugedik, Aslı; Atalar, Abdullah; Köymeni, Hayrettin (IEEE, 2013)In this work, we propose a new approach to obtain wider bandwidth for an airborne capacitive micromachined ultrasonic transducer (CMUT) cell without sacrificing sensitivity. This is done through employing the stiffening ...