Method and apparatus for providing dynamically variable time delay for ultrasound beamformer

Abstract

A phased array sector scanning ultrasonic system includes a separate receive channel for each respective element in an ultrasonic transducer array. Each receive channel imparts a delay to the echo signal produced by each respective element. The delayed echo signals are summed to form a steered, dynamically focused and dynamically windowed receive beam even when the transmit beam does not emanate from the center of the array. The receiver has a beamformer including a multiplicity of beamformer channels. The beamformer dynamically increases delays to each channel without introducing unwanted discontinuities, by combining and synchronizing a FIFO and an interpolator. The interpolator uses "Wallace tree" adders to accumulate bit-shifted versions of the inputs. The number of additions is less than the number of bits which would be needed to represent equivalent coefficients. This reduces the hardware relative to a conventional implementation which incorporates multipliers with shifts and adds equaling the number of bits in the coefficients.

Description

technical field [0001] The present invention relates generally to ultrasound imaging systems for forming ultrasound beams by delaying and summing return signals in a number of parallel channels. In particular, the present invention relates to means for providing the required beamforming latency for channel processing. Background technique [0002] Conventional ultrasound imaging systems include an array of ultrasound transducers that emit beams of ultrasound and then receive the beams reflected from the object of interest. For ultrasound imaging, the array typically has many transducers aligned in a line driven by independent voltages. By selecting the time delay (or phase) and magnitude of the applied voltages, the individual transducers can be controlled to produce ultrasonic waves that combine into a net ultrasonic wave that travels in a preferred vector direction and is focused along the beam at a selected point. Multiple transmissions may be used to obtain data repre...

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Dynamic changes in FIFO delays create discontinuities at t...

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