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Abstract:A compact all-digital duty-cycle and phase-skew correction circuit for quadrature data rate interface-based DRAM applications is presented. To improve the correction time, this work adopts a successive approximation register controller for both duty-cycle and phase-skew correction. The proposed correction circuit has been fabricated in a 65nm CMOS technology with a die area of 0.086mm [7] Y.-J. Min, et al.: "A 0.31-1 GHz fast-corrected duty-cycle corrector with successive approximation register for DDR DRAM applications," IEEE Trans.

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Synthetic aperture (SA) imaging techniques can enhance spatial resolution in medical ultrasound imaging. However, it suffers from the degradation of image quality close to a virtual source (e.g., transmit focal point) since there is no enough transmit acoustic field energy. In this paper, a new SA imaging technique (i.e., dynamic synthetic aperture, DSA) where the number of synthetic scanlines for acoustic field superposition is dynamically adjusted based on the transmit acoustic field analysis. For the DSA technique, the dynamic apodization window function was generated from the Field II simulation and applied in the phantom and in vivo experiments. The raw radio-frequency (RF) data for phantom and in vivo experiments were captured by an Ultrasonix's SonixTouch research platform connected with a SonixDAQ parallel acquisition system. From the phantom experiment, the proposed DSA method shows the enhanced spatial resolution over the depth compared to the conventional receive dynamic focusing (CRDF). In addition, it doesn't yield any artifacts associated with the lack of enough transmit acoustic energy shown in the conventional SA imaging technique. The consistent results were obtained with the in vivo breast data. This result indicates that the proposed DSA method could be used for enhancing image quality of medical ultrasound imaging.

Digital receive beamformer is one of the most important parts governing the performance and complexity of a medical ultrasound imaging system. In this presentation, we present a hardware efficient digital beamformer for small size ultrasound scanners, which is advantageous over the two most widely used beamforming schemes, interpolation beamformer and phase rotation beamformer, in terms of hardware complexity and performance. Interpolation beamformer requires a multi-tap interpolation filter for each channel to obtain 1/16f0 delay resolution. Phase rotation beamformer requires IQ demodulation and performs inter-channel delay compensation by shifting the phase of inphase and quadrature components. The proposed beamformer is identical to the interpolation beamformer except that it uses fractional delay (FD) filters to generate the delayed samples. FD filters were designed using least square error method to obtain an optimum performance for a given hardware complexity. The results show that the proposed method outperforms other beamforming methods.I.