A new architecture for ultrasound sigma-delta modulation beamformer

Beamforming techniques based on sigma-delta modulation (SDM) have been proposed to reduce the hardware complexity of the conventional delay-sum digital ultrasound beamformer. However, conventional single bit dynamic focusing methods are subject to signal distortion related to dynamic focusing delays. Moreover, the signal distortion in conventional single bit dynamic focusing SDM beamformers may prevent them from being used with pulse compression techniques. Several approaches have been proposed to minimize the signal distortion. These approaches increase the hardware complexity but cannot remove the distortion completely. In this paper, a block-based single bit dynamic focusing SDM beamformer is proposed, which can completely eliminate the demodulation error with a reduced hardware complexity. The proposed scheme does not cause any signal distortion by applying dynamic focusing delays for each imaging point to the relevant block of 1-bit SDM data in each channel. Computer simulation results show that the proposed SDM beamformer using 1 bit SDM data with 320 MHz data rate provides almost the same image quality as that of a traditional 8-bit delay-sum beamformer with 40 MHz sampling rate, with greatly reduced hardware complexity.