Low-noise ultrasound method and beamformer system for doppler processing
AssigneeSupertex, Inc.
InventorLazar Shifrin
Life of this patent
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Abstract
An ultrasonic low-noise analog beamformer for Doppler acquisition achieves high sensitivity by translating the frequency of the ultrasound echoes to an intermediate frequency, which is well above of the 1/f corner. This is accomplished by beamforming the downconverted RF signals instead of using their baseband representation. The baseband conversion, succeeding the beamformation, also incorporates the steps of clutter filtering and anti-aliasing. The invention is particularly suitable for low-voltage process technologies that support broadband applications.
Claims17
A method for receive beamforming in a CW Doppler ultrasound imaging system, comprising the steps of:
- receiving a plurality of RF ultrasound signals from a respective plurality of N transducer elements incorporated in an array, said RF signals are characterized by a frequency, fRF;
- translating the frequency of said RF signals to an intermediate frequency, fIF, to produce a respective plurality of IF signals, said intermediate frequency is above the flicker noise corner frequency;
- aligning the plurality of IF signals by a predetermined phasing;
- summing said plurality of IF signals to produce a beamformed IF output;
- and
- downconverting the beamformed IF output to a complex Doppler signal.
A low-noise ultrasonic CW Doppler beamformer for processing a plurality of RF signals produced by a transducer array, comprising:
- a plurality of Doppler channels, each Doppler channel operative to receive an RF signal from a respective transducer element and to produce a phase-rotated signal at an intermediate frequency IF responsive to said RF signal and to a local oscillator clock;
- an N-input summer coupled to said plurality of Doppler channels for summing all of said phase-rotated signals and to produce a beamformed IF signal;
- a downstream processor coupled to said N-input summer operative to downconvert said beamformed IF signal and to provide an approximately clutter-free complex signal, said processor having an input signal terminal;
- a multi-phase clock oscillator coupled to said plurality of Doppler channels for providing a plurality of k phase-shifted LO clocks having their phases evenly spaced within a 360° range.
A method for receive beamforming in a CW Doppler ultrasound imaging system, comprising the steps of:
- receiving a plurality of RF ultrasound signals from a respective plurality of N transducer elements incorporated in an array;
- translating the plurality of RF ultrasound signals to a plurality of intermediate frequency (IF) signals, each of said plurality of IF signals being above the flicker noise corner frequency;
- aligning the plurality of IF signals by a predetermined phasing;
- summing said plurality of IF signals to produce a beamformed IF output;
- and
- downconverting the beamformed IF output to a complex Doppler signal.
Dependencies are inferred from the claim text.