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For phased-array ultrasound imaging, alternative beamforming techniques and their VLSI circuits are studied to form a fully digital receive front-end hardware. In order to increase the timing accuracy in beamforming, a computationally efficient interpolation scheme to increase the sampling rate is examined. For adaptive beamforming, a phase aberration(More)
—An evolutionary algorithm is used to find three sets of binary sequences of length 49–100 suitable for the synchronization of digital communication systems. Optimization of the sets are done by taking into consideration the type of preamble used in data frames and the phase-lock mechanism of the communication system. The preamble is assumed to be either a(More)
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 (IFFT) are kernel processing blocks in an OFDM system, and are used for data (de)modulation. OFDM systems are increasingly required to be(More)
— Fast Fourier Transformation (FFT) and it's inverse (IFFT) are used in Orthogonal Frequency Division Multiplexing (OFDM) systems for data (de)modulation. The transformations are the kernel tasks in an OFDM implementation, and are the most processing-intensive ones. Recent trends in the electronic consumer market require OFDM implementations to be flexible,(More)
— A capacitive micromachined ultrasonic transducer (cMUT) is typically fabricated by concatenation of several cMUT cells with identical physical dimensions. If the membrane thickness is kept fixed, the radius of the cMUT determines the center frequency of operation. A smaller radius implies a greater center frequency. Therefore, it should be possible to put(More)
We present a parametric equivalent circuit model for a circular CMUT in collapsed mode. First, we calculate the collapsed membrane deflection, utilizing the exact electrical force distribution in the analytical formulation of membrane deflection. Then we develop a lumped element model of collapsed membrane operation. The radiation impedance for collapsed(More)
This paper describes a correction and an extension in the previously published large signal equivalent circuit model for a circular capacitive micromachined ultrasonic transducer (CMUT) cell. The force model is rederived so that the energy and power is preserved in the equivalent circuit model. The model is able to predict the entire behavior of CMUT until(More)
— In this work we define a performance measure for capacitive micromachined ultrasonic transducers (cMUT) in the form of a gain-bandwidth product to investigate the conditions that optimize the gain and bandwidth with respect to device dimensions , electrode size and electrical termination resistance. For the transmit mode, we define the figure of merit as(More)