A Column-Row-Parallel Ultrasound Imaging Architecture for 3-D Plane-Wave Imaging and Tx Second-Order Harmonic Distortion Reduction

We propose a column-row-parallel imaging frontend architecture for integrated and low-power 3-D medical ultrasound imaging. The column-row-parallel architecture offers linear-scaling interconnection, acquisition, and programming time with row-by-row or column-by-column operations, while supporting volumetric imaging functionality and fault-tolerance against possible transducer element defects with per-element controls. The combination of column-parallel selection logic, row-parallel selection logic, and per-element selection logic reaches a balance between flexible imaging aperture definition and manageable imaging data/control interface to a 2-D array. A 16 × 16 capacitive micromachined ultrasonic transducer (CMUT)-application-specific integrated circuit (ASIC) columnrow-parallel prototype is fabricated and assembled with a flipchip bonding process. It facilitates the 3-D plane-wave coherent compounding algorithm for volumetric imaging with a fast frame rate of 62.5 Hz and 46% improved lateral resolution with 10-angle compounding and a field of view volume of 2.3 mm in both azimuth and elevation, 8.5 mm in depth. At a hypothetically scaled up 64 × 64 array size, the frame rate can still be kept at 31.2 Hz for a volume of 40 mm in both azimuth and elevation, 150 mm in depth. An interleaved checkerboard pattern with in-phase (I) and quadrature (Q) excitations is also demonstrated for reducing CMUT second-harmonic distortion emission by up to 25 dB at the loss of 3-dB fundamental energy reduction. The method reduces nonlinear effects from both transducers and circuits and is a wide band technique that is applicable to arbitrary pulse shapes.