Full-array digital 3D ultrasound imaging system integrated with a matrix array transducer
Methods and systems for ultrasound imaging and beamforming with a matrix array of transducer elements are provided. Receive signals of each transducer array element are amplified. The amplified receive signal of each transducer array element is digitized. A delay and weight are applied on the amplified and digitized receive signals. The amplified, digitized, delayed, and weighted receive signals are summed across all transducer elements of the matrix array to form a dynamically focused receive beam. An application specific integrated circuit (ASIC) that is integrated with the matrix array of transducer elements performs such steps.
1 . A method comprising:
performing in an Application Specific Integrated Circuit (ASIC) upon which a matrix array of Piezoelectric Micromachined Ultrasound Transducer (pMUT) transducer elements are assembled, wherein an area of the ASIC matches an area of the matrix array of pMUT transducer elements:
(a) causing an independently delayed and weighted pulse to be transmitted from each of the pMUT transducer elements;
(b) amplifying receive signals of each pMUT transducer element;
(c) digitizing the amplified receive signal of each pMUT transducer element;
(d) applying a varying independent delay and weight on each of the amplified and digitized receive signals; and
(e) forming a focused receive beam by summing, across all pMUT transducer elements, the amplified, digitized, delayed, and weighted receive signals;
wherein pMUT-transducer-element-specific transmit delays and weights used in (a) and pMUT-transducer-element-specific varying independent receive delays and weights used in (d) are computed in real-time by at least one on-ASIC delay and weight computer.
2 . The method of claim 1 , wherein the ASIC is integrated with the matrix array of pMUT transducer elements.
3 . The method of claim 1 , wherein applying the varying independent delay and weight on each of the amplified and digitized receive signals is performed on a respective subarray of a plurality of subarrays of pMUT transducer elements of the matrix array of pMUT transducer elements and the method further comprises:
forming a respective micro beamformation of a plurality of micro beamformations by summing, across the respective subarray, the amplified, digitized, delayed, and weighted receive signals;
wherein summing across all the pMUT transducer elements includes summing the plurality of micro beamformations.
4 . The method of claim 1 , wherein a respective pMUT transducer element of the matrix array of pMUT transducer elements is switched from a transmit mode to a receive mode based on completion of pulse transmission by the respective pMUT transducer element and independent of a transmit mode or receive mode of other pMUT transducer elements of the matrix array of pMUT transducer elements.
5 . The method of claim 1 , further comprising forming transmit beams.
6 . The method of claim 1 , where two or more receive beams are formed per transmit event.
7 . The method of claim 1 , wherein the pMUT transducer elements of the matrix array are arranged in a square, rotated square, rectangular, parallelogram, hexagonal, circular, or spiral grid.
8 . The method of claim 1 , wherein amplifying the receive signals applies a depth varying amplification gain to the receive signals.
9 . The method of claim 1 , wherein a N-bit ADC digitizes the amplified receive signals at a sampling rate Fs.
10 . The method of claim 9 , wherein the N-bit ADC is selected from one or more of the group consisting of a pipeline ADC, a successive-approximation (SAR) ADC, a sigma-delta ADC, and/or a flash ADC.
11 . The method of claim 9 , wherein N is 1.
12 . The method of claim 9 , wherein the ADC input is dithered.
13 . The method of claim 9 , wherein the ADC sampling rate is programmable.
14 . The method of claim 13 , wherein the ADC sampling rate is a function of an imaging center frequency.
15 . The method of claim 1 , wherein the varying independent delay and weight applied on each of the amplified and digitized receive signals are one or more of element- or depth-dependent.
16 . The method of claim 1 , wherein the at least one on-ASIC delay and weight computer computes delays for each pMUT transducer element for a subset of depths with a CORDIC algorithm and interpolates between CORDIC-based delays for the in-between depth grid points.
17 . The method of claim 16 , wherein delay interpolations for the in-between depth grid points are linear.
18 . The method of claim 1 , wherein at least one on-ASIC delay and weight computer computes the weights for each pMUT transducer element based on depth, f-number and a distance between the pMUT transducer element and a beam origin.
19 . The method of claim 18 , wherein the weights are binary.
20 . The method of claim 18 , wherein the at least one on-ASIC delay and weight computer grows an active aperture with depth substantially as a circle or ellipsoid to reduce sidelobes.
21 . A system comprising
a matrix array of Piezoelectric Micromachined Ultrasound Transducer (pMUT) transducer elements; and
an Application Specific Integrated Circuit (ASIC) upon which the matrix array of pMUT transducer elements are assembled, wherein an area of the ASIC matches an area of the matrix array of pMUT transducer elements, and wherein the ASIC comprises:
at least one delay and weight computer;
a plurality of sets of electronic elements, wherein each set of electronic elements is coupled with a different pMUT transducer element of the matrix array and comprises a pulser, an amplifier, an analog-to-digital converter, and circuitry;
wherein:
(a) the pulsers are configured to cause an independently delayed and weighted pulse to be transmitted from each of the pMUT transducer elements;
(b) the amplifiers are configured to amplify receive signals of each pMUT transducer element;
(c) the analog-to-digital converters are configured to digitize the amplified receive signal of each pMUT transducer array element; and
(d) the circuitries are configured to apply a varying independent delay and weight on each of the amplified and digitized receive signals; and
a summer configured to sum, across all pMUT transducer elements, the amplified, digitized, delayed, and weighted receive signals to form a focused receive beam;
wherein pMUT-transducer-element-specific transmit delays and weights used by (a) and pMUT-transducer-element-specific varying independent receive delays and weights used by (d) are computed in real-time by at least one delay and weight computer.
22 . The system of claim 21 , wherein the ASIC is integrated with the matrix array of pMUT transducer elements.
23 . The system of claim 21 , wherein applying the varying independent delay and weight on each of the amplified and digitized receive signals is performed on a respective subarray of a plurality of subarrays of pMUT transducer elements of the matrix array of transducer elements and the summer is further configured to:
sum, across the respective subarray, the amplified, digitized, delayed, and weighted receive signals to form a respective micro beamformation of a plurality of micro beamformations; and
wherein summing across all the pMUT transducer elements includes summing the plurality of micro beamformations.
24 . The system of claim 21 , wherein a respective pMUT transducer element of the matrix array of pMUT transducer elements is switched from a transmit mode to a receive mode based on completion of pulse transmission by the respective pMUT transducer element and independent of a transmit mode or receive mode of other pMUT transducer elements of the matrix array of pMUT transducer elements.
25 . The system of claim 21 , wherein the ASIC is configured to form transmit beams.
26 . The system of claim 21 , where two or more receive beams are formed per transmit event.
27 . The system of claim 21 , wherein the pMUT transducer elements of the matrix array are arranged in a square, rotated square, rectangular, parallelogram, hexagonal, circular, or spiral grid.
28 . The system of claim 21 , wherein the amplifiers are configured to amplify the receive signals by applying a depth varying amplification gain to the receive signals.
29 . The system of claim 21 , wherein the ASIC further comprises a N-bit ADC to digitize the amplified receive signals at a sampling rate.
30 . The system of claim 29 , wherein the N-bit ADC is selected from one or more of the group consisting of a pipeline ADC, a successive-approximation (SAR) ADC, a sigma-delta ADC, and/or a flash ADC.
31 . The system of claim 29 , wherein N is 1.
32 . The system of claim 29 , wherein the ADC input is dithered.
33 . The system of claim 29 , wherein the ADC sampling rate is programmable.
34 . The system of claim 33 , wherein the ADC sampling rate is a function of an imaging center frequency.
35 . The system of claim 21 , wherein the varying independent delay and weight applied on each of the amplified and digitized receive signals are one or more of element- or depth-dependent.
36 . The system of claim 21 , wherein the at least one delay and weight computer computes delays for each pMUT transducer element for a subset of depths with a CORDIC algorithm and interpolates between CORDIC-based delays for the in-between depth grid points.
37 . The system of claim 36 , wherein delay interpolations for the in-between depth grid points are linear.
38 . The system of claim 21 , wherein the at least one delay and weight computer is configured to compute the weights for each pMUT transducer element based on depth, f-number and a distance between the pMUT transducer element and a beam origin.
39 . The system of claim 38 , wherein the weights are binary.
40 . The system of claim 38 , wherein the at least one delay and weight computer grows an active aperture with depth substantially as a circle or ellipsoid to reduce sidelobes.