Delta-sigma beamformer and method for beamforming

An ultrasound imaging system comprising:

• a display screen;
• a beamsummer;
• a plurality of transducer elements arranged in an array;
• a plurality of channels, where each of the channels is configured to carry signals from one or more of the plurality of transducer elements;
• a plurality of delta-sigma modules, where each of the delta-sigma modules is connected to one of the plurality of channels, where each of the delta-sigma modules comprises:
• a delta-sigma modulator configured to receive analog ultrasound signals from one of the plurality of channels and output a delay line including a plurality of samples based on the analog ultrasound signals;
• a comb filter connected to the delta-sigma modulator and configured to output a difference between two of the plurality of samples in the delay line;
• an accumulator module comprising an accumulator connected to the comb filter, where the accumulator module is configured to integrate signals received from the comb filter during a non-delay-expansion period and transmit the integrated signals to the beamsummer during the non-delay expansion period, and where the accumulator module is configured to output a zero to the beamsummer during a delay-expansion period.

A method for beamforming ultrasound signals, the method comprising:

• providing analog ultrasound signals from a plurality of transducer elements to a delta-sigma modulator associated with one of a plurality of channels;
• outputting a delay line from the delta sigma modulator, the delay line including a plurality of samples based on the analog ultrasound signals;
• outputting, with a comb filter, a plurality of differences between samples at two different locations in the delay line;
• providing the plurality of differences to an accumulator during a non-delay-expansion period;
• generating an output signal with the accumulator during the non-delay-expansion period, where the output signal comprises an integration based on the plurality of differences;
• providing the output signal to a beamsummer during the non-delay-expansion period;
• activating a switch during a delay-expansion period, where activating the switch stops the plurality of differences from being sent to the accumulator during the delay-expansion period and causes a value of zero to be sent to the beamsummer during the delay-expansion period;
• generating an image based on both the output signal and the value of zero provided to the beamsummer;
• and
• displaying the image.