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Proceedings Paper

A delta-sigma beamformer with integrated apodization
Author(s): Borislav Gueorguiev Tomov; Matthias Bo Stuart; Martin Christian Hemmsen; Jørgen Arendt Jensen
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Paper Abstract

This paper presents a new design of a discrete time Delta-Sigma (ΔΣ) oversampled ultrasound beamformer which integrates individual channel apodization by means of variable feedback voltage in the Delta-Sigma analog to digital (A/D) converters. The output bit-width of each oversampled A/D converter remains the same as in an unmodified one. The outputs of all receiving channels are delayed and summed, and the resulting multi-bit sample stream is filtered and decimated to become an image line. The simplicity of this beamformer allows the production of high-channel-count or very compact beamformers suitable for 2-D arrays or compact portable scanners. The new design is evaluated using measured data from the research scanner SARUS and a BK-8811 192 element linear array transducer (BK Medical, Herlev, Denmark), insonifying a water-filled wire phantom containing four wires orthogonal to the image plane. The data are acquired using 12-bit flash A/D converters at a sampling rate of 70 MHz, and are then upsampled off-line to 560 MHz for input to the simulated ΔΣ beamformer. The latter generates a B-mode image which is compared to that produced by a digital beamformer that uses 10-bit A/D converters. The performance is evaluated by comparing the width of the wire images at half amplitude and the noise level of the images. The ΔΣ beamformer resolution has been found to be identical to that of the multi-bit A/D beamforming architecture, while the noise floor is elevated by approximately 6 dB.

Paper Details

Date Published: 29 March 2013
PDF: 7 pages
Proc. SPIE 8675, Medical Imaging 2013: Ultrasonic Imaging, Tomography, and Therapy, 86750R (29 March 2013); doi: 10.1117/12.2006731
Show Author Affiliations
Borislav Gueorguiev Tomov, Technical Univ. of Denmark (Denmark)
Matthias Bo Stuart, Technical Univ. of Denmark (Denmark)
Martin Christian Hemmsen, Technical Univ. of Denmark (Denmark)
Jørgen Arendt Jensen, Technical Univ. of Denmark (Denmark)

Published in SPIE Proceedings Vol. 8675:
Medical Imaging 2013: Ultrasonic Imaging, Tomography, and Therapy
Johan G. Bosch; Marvin M. Doyley, Editor(s)

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