Improved ultrasound digital beamforming using single-bit sigma-delta modulators with band-pass decimation filters

In this study, a novel hardware efficient digital ultrasound beamformer using single-bit second-order Σ-Δ modulators incorporated with band-pass decimation filters is presented. Beside the reduced size, cost and power consumption of the phased array front-end circuitry, there are significant image artifacts introduced by Σ-Δ beamformers. The elevated noise floor due to the repeated samples in dynamic focusing is greatly reduced by hardware efficient band-pass filters in the decimation stage following the beam summation. The B-scan images using experimental phantom data have shown that the proposed structure achieves significant improvements over the image resolution constructed by a conventional Σ-Δ beamformer. This novel structure ensures high quality B-scan images by preserving the hardware simplicity of the conventional single-bit Σ-Δ beamformers.