Delay interpolator for digital phased array ultrasound beamformers

An ultrasound beamformer for processing received signals from an array of ultrasound transducer elements, comprising:

• a plurality of processing channels, one coupled to each transducer element of the array, each processing channel comprising:
• digitizing means for converting the received signal to digital samples at a predetermined sampling rate f, and
• delay means for delaying said digital samples by predetermined delays to provide delayed digital samples, said delay means comprising a delay interpolator including an FIR digital filter having programmable means responsive to delay control information representative of filter coefficients for delaying the digital samples by different delays that are quantized in increments less than the sampling period 1/f, wherein one or more of said filter coefficients are of the form 1/2.sup.m where m is an integer, and wherein said FIR digital filter comprises means for multiplying consecutive ones of said digital samples by respective ones of said filter coefficients by shifting the bits of said digital samples by m bit positions in response to said delay control information, to provide intermediate samples, said FIR digital filter further comprising summing means for summing said intermediate samples to provide said delayed digital samples;
• summing means for summing said delayed digital samples to form output samples that are representative of a received beam;
• and
• control means for supplying said delay control information to said delay means in each of said processing channels.

In an ultrasound beamformer wherein received signals from plural transducer elements of a transducer array are converted to digital samples at a sampling frequency f, the digital samples are delayed by selected delays and the delayed digital samples are summed to form a focused received beam, a delay interpolator for delaying the digital samples in each channel by selected delays that are quantized in increments less than the sampling period 1/f, comprising:

• an FIR digital filter including programmable means responsive to delay control information for delaying the digital samples by different delays that are quantized in increments less than the sampling period;
• control means responsive to a delay control signal representative of a desired delay for supplying said delay control information to said FIR digital filter;
• first means for storing a first group of consecutive digital samples representative of a first beam;
• second means for storing a second group of consecutive digital samples representative of a second beam;
• and
• selector means for sequentially supplying said first group of consecutive digital samples and said second group of consecutive digital samples to said FIR digital filter such that said FIR digital filter performs time multiplexed processing of digital samples of said first beam and said second beam.