A Comparison of the Lookup Table and On-The-Fly Calculation Methods for the Beamforming Control Unit

Modern diagnostic ultrasound beamformers require extensive delay information for the focusing of each focal point along the image lines. For a typical beamforming system with dynamic delays, the beamforming control unit is used to calculate the delay information and generate instant delay profiles in order to achieve dynamic focusing beamforming. In this study, the beamforming control unit targeted at a home-based portable delta-sigma oversampled ultrasound beamforming setup was developed. The beamforming principle for 1-D linear transducer array with dynamic aperture was exploited, and three delay generation methods including complete lookup table, compressed lookup table with delta encoding and general parametric algorithm were investigated, implemented and synthesized using VHDL for a FPGA device Spartan-3E XC3S500E. A comparison was performed among the three delay generation methods on their performances in terms of overall logic resource usage and power consumption.