PMUT Array Receive Beamforming for Spurious Reflection Rejection
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Solution Overview
Problem
Conventional piezoelectric ultrasonic transducers face limitations in achieving high-frequency operation with minimal acoustic diffraction and efficient signal generation and sensing, particularly in applications requiring high resolution and low spurious reflection rejection.
Innovation Solution
The development of a Piezoelectric Micromachined Ultrasonic Transducer (PMUT) device with a center pinned membrane and interior support structure, optimized for high-frequency operation, which includes a substrate, edge support, and a piezoelectric layer with electrodes, allowing for efficient ultrasonic signal generation and sensing, and employing phase delayed transmission patterns for improved beamforming and signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional piezoelectric ultrasonic transducers are used, then signal generation and sensing can be achieved, but acoustic diffraction occurs and spurious reflections are generated at high frequencies
Solution Approach 1:
The ultrasonic transducer array is divided into multiple independently controllable transducer elements that can be selectively activated. This segmentation allows for beamforming techniques to be applied, where signals from multiple elements are combined with specific phase and amplitude relationships to focus acoustic energy in desired directions while suppressing diffraction and spurious reflections.
Solution Approach 2:
Different regions of the ultrasonic transducer array can be assigned different operational characteristics. The patent applies receive patterns that selectively activate specific subsets of transducers based on the direction and origin of incoming acoustic signals, optimizing local signal quality while minimizing harmful effects from other regions.
2Measurement precision
If high-frequency operation is achieved, then resolution is improved, but acoustic diffraction increases and spurious reflections are generated
Solution Approach 1:
The system dynamically adjusts the receive patterns and beamforming parameters based on the operational requirements. By selectively activating different combinations of transducer elements and adjusting their phase relationships in real-time, the system maintains high resolution at high frequencies while dynamically suppressing acoustic diffraction and spurious reflections through adaptive signal processing.
Solution Approach 2:
The patent changes the operational parameters of the ultrasonic transducers, specifically the phase and amplitude of signals from different elements. By applying phase delays and amplitude weighting in receive beamforming, the system achieves high-frequency operation with improved resolution while minimizing acoustic diffraction and spurious reflections through parameter optimization.
3Reliability
If receive patterns are selectively applied, then signal quality is improved, but device complexity increases due to multiple switches and control circuitry
Solution Approach 1:
The ultrasonic transducer array is designed with multi-functionality, where the same physical transducer elements can be configured for different receive patterns through electronic control. This universal design allows a single array structure to perform multiple sensing functions without requiring separate hardware for each pattern, reducing overall device complexity while maintaining signal quality.
Solution Approach 2:
The system uses digital signal processing and software-based beamforming to achieve selective receive patterns, allowing the transducer array to self-configure for different operational modes. This approach replaces complex analog switching networks with programmable control logic, simplifying the hardware while maintaining the ability to selectively apply different receive patterns for optimal signal quality.
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
The PMUT device achieves high-frequency operation with reduced acoustic diffraction, enabling better rejection of spurious reflections and enhanced signal quality, suitable for applications such as fingerprint sensing and other biometric systems.
Implementation Method 1
a piezoelectric layer (110) between the first and second electrodes (106, 108), wherein the piezoelectric layer (110) is configured to vibrate in response to an actuation voltage applied across the first and second electrodes (106, 108)
Implementation Method 2
a piezoelectric layer (110) between the first and second electrodes (106, 108), wherein the piezoelectric layer (110) is configured to vibrate in response to an actuation voltage applied across the first and second electrodes (106, 108)
Implementation Method 3
Piezoelectric materials are widely utilized in piezoelectric ultrasonic transducers to generate acoustic waves based on an actuation voltage applied to electrodes
Data Source
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AI summary
An ultrasonic sensor includes a two-dimensional array of ultrasonic transducers including a plurality of sub-arrays of ultrasonic transducers, wherein a sub-array of ultrasonic transducers of the plurality of sub-arrays of ultrasonic transducers is independently controllable, and wherein a sub-array of ultrasonic transducers has an associated receive channel. A plurality of shift registers is configured to select a receive pattern of ultrasonic transducers of the two-dimensional array of ultrasonic transducers to activate during a receive operation. An array controller is configured to control selection of the ultrasonic transducers during the receive operation according to the receive pattern and configured to shift a position of the receive pattern within the plurality of shift registers such that the ultrasonic transducers activated during the receive operation moves relative to and within the two-dimensional array of ultrasonic transducers.