Correlation-based correction of sound velocity inhomogeneities using delta-sigma modulators.

Delta-sigma (deltasigma) modulator based beamformers have been proposed for high-quality ultrasonic imaging. Due to the high sampling rate and single bit data width, the cost and complexity of the receive beamformer can be significantly reduced. It was shown that with proper dynamic focusing controls, equivalent image quality could be achieved with an adequate signal-to-quantization noise ratio (SQNR). In this paper, deltasigma modulator based beamformers are used for correlation-based phase aberrations correction of sound velocity inhomogeneities in the body. It is shown that the correction can be efficiently implemented at a performance level similar to that of a conventional radio frequency (rf) beamformer. In addition, more than 6 dB contrast improvement is demonstrated. The different dynamic focusing techniques are also investigated in the context of phase aberration correction. It is shown that the single bit dynamic focusing approach does not affect the overall performance of phase aberration correction.