The Experts below are selected from a list of 50586 Experts worldwide ranked by ideXlab platform
Tadahiro Kuroda - One of the best experts on this subject based on the ideXlab platform.
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a 40 gb s cmos clocked comparator with bandwidth modulation technique
IEEE Journal of Solid-state Circuits, 2005Co-Authors: Y Okaniwa, Hirotaka Tamura, Masaya Kibune, D Yamazaki, Tszshing Cheung, Junji Ogawa, Nestoras Tzartzanis, William W Walker, Tadahiro KurodaAbstract:A differential comparator that can sample 40-Gb/s signals and that operates off a single 1.2-V supply was designed and fabricated in 0.11-/spl mu/m standard CMOS technology. It consists of a front-end sampler, a regenerative stage, and a clocked amplifier to provide a small Aperture Time and a high toggle rate. The clocked amplifier employs a bandwidth modulation technique that switches the feedback gain to reduce the reset Time while keeping the effective gain high. We confirmed that the comparator receives a 40-Gb/s data stream at a toggle rate of 10 GHz with bit error rate less than 10/sup -12/ by laboratory measurements.
Guisheng Liao - One of the best experts on this subject based on the ideXlab platform.
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narrowband rfi suppression for sar system via fast implementation of joint sparsity and low rank property
IEEE Transactions on Geoscience and Remote Sensing, 2018Co-Authors: Yan Huang, Guisheng LiaoAbstract:The synthetic Aperture radar (SAR), as a wideband radar system, operates over a large frequency band ranging from the low very high frequency to millimeter waves. It often overlaps in frequency with other radio-frequency systems including radio, television, and cellular networks. Therefore, radio-frequency interference (RFI) suppression is the severe test for SAR systems. Recently, some methods are proposed to suppress the RFI based on the sparse recovery in range-frequency domain and low-rank extraction in the azimuth dimension. However, all the previous methods exploit one property of the RFI, which may leave the room for performance improvement. Hence, in this paper, we propose three methods to jointly exploit the sparsity and low-rank property of RFI. We first include the sparse term and low-rank term of the RFI in the objective function to separate the RFI and the useful signal, which is defined as the joint sparsity and low-rank property method. It has better performance but heavier computational burden than the algorithm employing only the low-rank property. Then, we use row-sparse (RS) concept in lieu of the two properties, since the narrowband RFI has relatively stable frequencies during the synthetic Aperture Time. The RS method avoids the low-rank optimization and dramatically decrease the computational burden. Also for the real radar system, the sampling frequency is commonly larger than the frequency bandwidth. Therefore, there are some redundant data in the received signal. We exploit both the downsampling operation and the RS concept to speed up the convergence, which is called the fast row-sparse (FRS) method. The FRS method can further eliminate the out-of-mainband RFI. The real SAR data are provided to demonstrate the effectiveness of the three proposed methods.
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an approach for refocusing of ground fast moving target and high order motion parameter estimation using radon high order Time chirp rate transform
Digital Signal Processing, 2016Co-Authors: Penghui Huang, Guisheng Liao, Zhiwei YangAbstract:Long synthetic Aperture Time can improve the imaging quality of a ground moving target, whereas a moving target may be severely smeared in the cross-range image due to the range migration and the Doppler frequency migration. In this paper, the effects of the third-order Doppler broadening and Doppler ambiguity of a fast-moving target are considered. To address these issues, a novel motion parameter estimation method named high-order Time-chirp rate transform (HTRT) is proposed, and then a new synthetic Aperture radar (SAR) imaging method based on Radon-HTRT (RHTRT) for a ground moving target is developed. The major contributions are as follows: 1) The proposed SAR imaging method can eliminate the Doppler ambiguity effect. 2) The proposed method can realize longer Time coherent integration than Radon-Fourier transform (RFT) and Radon-fractional Fourier transform (RFRFT) methods. 3) The proposed method is computationally efficient since HTRT can obtain the motion parameters of a moving target via performing the 2-dimensional (2-D) fast Fourier transform (FFT). Both the simulated and real data processing results show that the proposed method can finely image a ground moving target in a high signal-to-clutter and noise ratio (SCNR) environment.
Y Okaniwa - One of the best experts on this subject based on the ideXlab platform.
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a 40 gb s cmos clocked comparator with bandwidth modulation technique
IEEE Journal of Solid-state Circuits, 2005Co-Authors: Y Okaniwa, Hirotaka Tamura, Masaya Kibune, D Yamazaki, Tszshing Cheung, Junji Ogawa, Nestoras Tzartzanis, William W Walker, Tadahiro KurodaAbstract:A differential comparator that can sample 40-Gb/s signals and that operates off a single 1.2-V supply was designed and fabricated in 0.11-/spl mu/m standard CMOS technology. It consists of a front-end sampler, a regenerative stage, and a clocked amplifier to provide a small Aperture Time and a high toggle rate. The clocked amplifier employs a bandwidth modulation technique that switches the feedback gain to reduce the reset Time while keeping the effective gain high. We confirmed that the comparator receives a 40-Gb/s data stream at a toggle rate of 10 GHz with bit error rate less than 10/sup -12/ by laboratory measurements.
Murat A Tekalp - One of the best experts on this subject based on the ideXlab platform.
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superresolution video reconstruction with arbitrary sampling lattices and nonzero Aperture Time
IEEE Transactions on Image Processing, 1997Co-Authors: Andrew J Patti, Muhammed Ibrahim Sezan, Murat A TekalpAbstract:Printing from an NTSC source and conversion of NTSC source material to high-definition television (HDTV) format are some of the applications that motivate superresolution (SR) image and video reconstruction from low-resolution (LR) and possibly blurred sources. Existing methods for SR image reconstruction are limited by the assumptions that the input LR images are sampled progressively, and that the Aperture Time of the camera is zero, thus ignoring the motion blur occurring during the Aperture Time. Because of the observed adverse effects of these assumptions for many common video sources, this paper proposes (i) a complete model of video acquisition with an arbitrary input sampling lattice and a nonzero Aperture Time, and (ii) an algorithm based on this model using the theory of projections onto convex sets to reconstruct SR still images or video from an LR Time sequence of images. Experimental results with real video are provided, which clearly demonstrate that a significant increase in the image resolution can be achieved by taking the motion blurring into account especially when there exists large interframe motion.
D Yamazaki - One of the best experts on this subject based on the ideXlab platform.
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a 40 gb s cmos clocked comparator with bandwidth modulation technique
IEEE Journal of Solid-state Circuits, 2005Co-Authors: Y Okaniwa, Hirotaka Tamura, Masaya Kibune, D Yamazaki, Tszshing Cheung, Junji Ogawa, Nestoras Tzartzanis, William W Walker, Tadahiro KurodaAbstract:A differential comparator that can sample 40-Gb/s signals and that operates off a single 1.2-V supply was designed and fabricated in 0.11-/spl mu/m standard CMOS technology. It consists of a front-end sampler, a regenerative stage, and a clocked amplifier to provide a small Aperture Time and a high toggle rate. The clocked amplifier employs a bandwidth modulation technique that switches the feedback gain to reduce the reset Time while keeping the effective gain high. We confirmed that the comparator receives a 40-Gb/s data stream at a toggle rate of 10 GHz with bit error rate less than 10/sup -12/ by laboratory measurements.