cMUT Array Tiling via Fixed Via Position and Overlapping Circuit
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Solution Overview
Problem
Existing ultrasound transducer arrays face challenges in scalability and modular design due to limitations in ASIC design flexibility and the need for seamless tiling of transducer modules, which can result in image artifacts and increased costs.
Innovation Solution
The solution involves a control circuit with an array of circuit portions and capacitive micromachined ultrasound transducer elements, where the transducer elements overlap the circuit area, allowing for a smaller pitch in at least one direction, enabling tiling and modular design by using vias to connect each cMUT element to the circuit portions, and allowing the same ASIC design to be used for different transducer pitches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If transducer arrays are tiled to exceed lithographic reticle area, then larger transducer dimensions are achieved, but image quality deteriorates due to seam artifacts
Solution Approach 1:
The transducer array is divided into multiple independently fabricatable modules, each within lithographic reticle limits. These modules are then tiled together to form a large-scale array, enabling production of transducers exceeding 2.5cm dimensions while maintaining manufacturing precision through standardized module replication
Solution Approach 2:
The patent introduces specific intermediary structures including seal rings and scribe streets that mediate between adjacent transducer modules. These intermediaries provide mechanical support, electrical isolation, and stress relief, ensuring seamless integration that prevents image artifacts while enabling tiling of multiple modules
2Manufacturing precision
If ASIC design is customized for specific transducer configurations, then transducer performance is optimized, but manufacturing cost increases due to repeated ASIC redesign
Solution Approach 1:
The patent designs a universal ASIC architecture with standardized control cells that can interface with multiple transducer element types and configurations. This universal controller uses programmable parameters to adapt to different transducer pitches, frequencies, and aperture sizes, eliminating the need for custom ASIC designs for each transducer variant while maintaining optimized performance
Solution Approach 2:
The patent enables transducer configuration changes through parameter adjustments in the standardized control cells rather than physical design changes. By modifying operational parameters such as element pitch, frequency, and aperture dimensions in software, the same ASIC design can be reused across different transducer applications, significantly reducing manufacturing costs
3Device complexity
If transducer elements are pitch-matched to ASIC control cells, then integration is simplified, but design flexibility is lost for varying transducer configurations
Solution Approach 1:
The patent introduces a decoupling layer between the physical transducer element pitch and the ASIC control cell pitch by using intermediate routing layers and buffer elements. This allows the ASIC control cells to maintain a fixed pitch while the transducer elements can be arranged at different pitches, providing design flexibility without increasing integration complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the formation of regular arrays of cMUT elements, facilitates tiling and modular design, reduces costs by allowing reuse of ASIC designs, and improves image quality by minimizing seam-related artifacts in large transducer arrays.
Implementation Method 1
capacitive micromachined ultrasound transducer, cMUT, elements provided over the top of (or arranged to overlay) the control circuit
Implementation Method 2
an array of vias, with at least one via providing a coupling between each cMUT element and a respective one of the circuit portions beneath
Data Source
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AI summary
An ultrasound transducer has a control circuit with an array of circuit portions, the used ones of which defining a circuit area. cMUT elements are provided over the top of the control circuit. Vias provide a coupling between each cMUT element and a respective one of the circuit portions beneath. At least some vias are located beneath the bottom electrode of the cMUT element and each via connects to the respective circuit portion at a same position relative to the circuit portion. The array of cMUT elements overlaps at least one side of the circuit area. The fixed via position makes the circuit design simpler, and the overlap enables tiling or else enables a modular design in which different cMUT designs may be used with the same circuit.