Abstract: Some disclosed implementations include an ultrasonic sensor stack and an acoustic resonator. The acoustic resonator may be configured to enhance ultrasonic waves transmitted by the ultrasonic sensor stack in an ultrasonic frequency range that is suitable for ultrasonic fingerprint sensors. In some examples, the acoustic resonator may include one or more low-impedance layers residing between a first higher-impedance layer and a second higher-impedance layer. Each of the one or more low-impedance layers may have a lower acoustic impedance than an acoustic impedance of the first higher-impedance layer or an acoustic impedance of the second higher-impedance layer. At least one low-impedance layer may have a thickness corresponding to a multiple of a half wavelength at a peak frequency of the acoustic resonator. The peak frequency may be within a frequency range from 1 MHz. to 20 MHz.

Abstract: Some disclosed implementations include an ultrasonic sensor stack and an acoustic resonator. The acoustic resonator may be configured to enhance ultrasonic waves transmitted by the ultrasonic sensor stack in an ultrasonic frequency range that is suitable for ultrasonic fingerprint sensors. In some examples, the acoustic resonator may include one or more low-impedance layers residing between a first higher-impedance layer and a second higher-impedance layer. Each of the one or more low-impedance layers may have a lower acoustic impedance than an acoustic impedance of the first higher-impedance layer or an acoustic impedance of the second higher-impedance layer. At least one low-impedance layer may have a thickness corresponding to a multiple of a half wavelength at a peak frequency of the acoustic resonator. The peak frequency may be within a frequency range from 1 MHz. to 20 MHz.

Abstract: Some disclosed implementations include an ultrasonic sensor stack and an acoustic resonator. The acoustic resonator may be configured to enhance ultrasonic waves transmitted by the ultrasonic sensor stack in an ultrasonic frequency range that is suitable for ultrasonic fingerprint sensors. In some examples, the acoustic resonator may include one or more low-impedance layers residing between a first higher-impedance layer and a second higher-impedance layer. Each of the one or more low-impedance layers may have a lower acoustic impedance than an acoustic impedance of the first higher-impedance layer or an acoustic impedance of the second higher-impedance layer. At least one low-impedance layer may have a thickness corresponding to a multiple of a half wavelength at a peak frequency of the acoustic resonator. The peak frequency may be within a frequency range from 1 MHz. to 20 MHz.

Abstract: Some disclosed implementations include an ultrasonic sensor stack and an acoustic resonator. The acoustic resonator may be configured to enhance ultrasonic waves transmitted by the ultrasonic sensor stack in an ultrasonic frequency range that is suitable for ultrasonic fingerprint sensors. In some examples, the acoustic resonator may include one or more low-impedance layers residing between a first higher-impedance layer and a second higher-impedance layer. Each of the one or more low-impedance layers may have a lower acoustic impedance than an acoustic impedance of the first higher-impedance layer or an acoustic impedance of the second higher-impedance layer. At least one low-impedance layer may have a thickness corresponding to a multiple of a half wavelength at a peak frequency of the acoustic resonator. The peak frequency may be within a frequency range from 1 MHz. to 20 MHz.

Abstract: Systems and methods for multi-spectral ultrasonic imaging are disclosed. In one embodiment, a finger is scanned at a plurality of ultrasonic scan frequencies. Each scan frequency provides an image information set describing a plurality of pixels of the finger including a signal-strength indicating an amount of energy reflected from a surface of a platen on which a finger is provided. For each of the pixels, the pixel output value corresponding to each of the scan frequencies is combined to produce a combined pixel out put value for each pixel. Systems and methods for improving the data capture of multi-spectral ultrasonic imaging are also disclosed.

Abstract: A piezoelectric micromechanical ultrasonic transducer (PMUT) includes a multilayer stack disposed on a substrate. The multilayer stack may include an anchor structure disposed over the substrate, a piezoelectric layer stack disposed over the anchor structure, and a mechanical layer disposed proximate to the piezoelectric layer stack. The piezoelectric layer stack may be disposed over a cavity. The mechanical layer may seal the cavity and, together with the piezoelectric layer stack, is supported by the anchor structure and forms a membrane over the cavity, the membrane being configured to undergo one or both of flexural motion and vibration when the PMUT receives or transmits ultrasonic signals.

Abstract: Techniques describe structures and methods for generating larger output signals and improving image quality of ultrasonic sensors by inclusion of an acoustic cavity in the sensor stack. In some embodiments, an ultrasonic sensor unit may be tuned during manufacturing or during a provisioning phase to work with different thicknesses and materials. In some embodiments, a standing wave signal may be generated using an acoustic cavity in the ultrasonic sensor unit for capturing an ultrasonic image of an object placed on a sensor surface. In some implementations, the ultrasonic sensor may include an ultrasonic transmitter, a piezoelectric receiver, a thin film transistor (TFT) layer and a TFT substrate positioned between the transmitter and the receiver, one or more adhesive layers, and optional cover materials and coatings. The thickness, density and speed of sound of the sensor materials and associated adhesive attachment layers may be used to attain the desired acoustic cavity and improved performance.

Abstract: A piezoelectric micromechanical ultrasonic transducer (PMUT) includes a diaphragm disposed over a cavity, the diaphragm including a piezoelectric layer stack including a piezoelectric layer, a first electrode electrically coupled with transceiver circuitry, and a second electrode electrically coupled with the transceiver circuitry. The first electrode may be disposed in a first portion of the diaphragm, and the second electrode may be disposed in a second, separate, portion of the diaphragm. Each of the first and the second electrode is disposed on or proximate to a first surface of the piezoelectric layer, the first surface being opposite from the cavity. The PMUT is configured to transmit first ultrasonic signals by way of the first electrode during a first time period and to receive second ultrasonic signals by way of the second electrode during a second time period, the first time period and the second time period being at least partially overlapping.

Abstract: Embodiments of an ultrasonic button and methods for using the ultrasonic button are disclosed. In one embodiment, an ultrasonic button may include an ultrasonic transmitter configured to transmit an ultrasonic wave, a piezoelectric receiver layer configured to receive a reflected wave of the ultrasonic wave, a platen layer configured to protect the ultrasonic transmitter and the piezoelectric receiver layer, a first matching layer configured to match an acoustic impedance of the platen layer with an acoustic impedance of ridges of a finger, and an ultrasonic sensor array configured to detect the finger using the reflected wave.

Abstract: Techniques describe structures and methods for generating larger output signals and improving image quality of ultrasonic sensors by inclusion of an acoustic cavity in the sensor stack. In some embodiments, an ultrasonic sensor unit may be tuned during manufacturing or during a provisioning phase to work with different thicknesses and materials. In some embodiments, a standing wave signal may be generated using an acoustic cavity in the ultrasonic sensor unit for capturing an ultrasonic image of an object placed on a sensor surface. In some implementations, the ultrasonic sensor may include an ultrasonic transmitter, a piezoelectric receiver, a thin film transistor (TFT) layer and a TFT substrate positioned between the transmitter and the receiver, one or more adhesive layers, and optional cover materials and coatings. The thickness, density and speed of sound of the sensor materials and associated adhesive attachment layers may be used to attain the desired acoustic cavity and improved performance.

Abstract: Techniques describe structures and methods for generating larger output signals and improving image quality of ultrasonic sensors by inclusion of an acoustic cavity in the sensor stack. In some embodiments, an ultrasonic sensor unit may be tuned during manufacturing or during a provisioning phase to work with different thicknesses and materials. In some embodiments, a standing wave signal may be generated using an acoustic cavity in the ultrasonic sensor unit for capturing an ultrasonic image of an object placed on a sensor surface. In some implementations, the ultrasonic sensor may include an ultrasonic transmitter, a piezoelectric receiver, a thin film transistor (TFT) layer and a TFT substrate positioned between the transmitter and the receiver, one or more adhesive layers, and optional cover materials and coatings. The thickness, density and speed of sound of the sensor materials and associated adhesive attachment layers may be used to attain the desired acoustic cavity and improved performance.

Abstract: Systems and methods for multi-spectral ultrasonic imaging are disclosed. In one embodiment, a finger is scanned at a plurality of ultrasonic scan frequencies. Each scan frequency provides an image information set describing a plurality of pixels of the finger including a signal-strength indicating an amount of energy reflected from a surface of a platen on which a finger is provided. For each of the pixels, the pixel output value corresponding to each of the scan frequencies is combined to produce a combined pixel out put value for each pixel. Systems and methods for improving the data capture of multi-spectral ultrasonic imaging are also disclosed.

Abstract: A piezoelectric micromechanical ultrasonic transducer (PMUT) includes a diaphragm disposed over a cavity, the diaphragm including a piezoelectric layer stack including a piezoelectric layer, a first electrode electrically coupled with transceiver circuitry, and a second electrode electrically coupled with the transceiver circuitry. The first electrode may be disposed in a first portion of the diaphragm, and the second electrode may be disposed in a second, separate, portion of the diaphragm. Each of the first and the second electrode is disposed on or proximate to a first surface of the piezoelectric layer, the first surface being opposite from the cavity. The PMUT is configured to transmit first ultrasonic signals by way of the first electrode during a first time period and to receive second ultrasonic signals by way of the second electrode during a second time period, the first time period and the second time period being at least partially overlapping.

Abstract: Embodiments of an ultrasonic button and methods for using the ultrasonic button are disclosed. In one embodiment, an ultrasonic button may include an ultrasonic transmitter configured to transmit an ultrasonic wave, a piezoelectric receiver layer configured to receive a reflected wave of the ultrasonic wave, a platen layer configured to protect the ultrasonic transmitter and the piezoelectric receiver layer, a first matching layer configured to match an acoustic impedance of the platen layer with an acoustic impedance of ridges of a finger, and an ultrasonic sensor array configured to detect the finger using the reflected wave.

Abstract: Techniques describe structures and methods for generating larger output signals and improving image quality of ultrasonic sensors by inclusion of an acoustic cavity in the sensor stack. In some embodiments, an ultrasonic sensor unit may be tuned during manufacturing or during a provisioning phase to work with different thicknesses and materials. In some embodiments, a standing wave signal may be generated using an acoustic cavity in the ultrasonic sensor unit for capturing an ultrasonic image of an object placed on a sensor surface. In some implementations, the ultrasonic sensor may include an ultrasonic transmitter, a piezoelectric receiver, a thin film transistor (TFT) layer and a TFT substrate positioned between the transmitter and the receiver, one or more adhesive layers, and optional cover materials and coatings. The thickness, density and speed of sound of the sensor materials and associated adhesive attachment layers may be used to attain the desired acoustic cavity and improved performance.

Abstract: A piezoelectric micromechanical ultrasonic transducer (PMUT) includes a multilayer stack disposed on a substrate. The multilayer stack may include an anchor structure disposed over the substrate, a piezoelectric layer stack disposed over the anchor structure, and a mechanical layer disposed proximate to the piezoelectric layer stack. The piezoelectric layer stack may be disposed over a cavity. The mechanical layer may seal the cavity and, together with the piezoelectric layer stack, is supported by the anchor structure and forms a membrane over the cavity, the membrane being configured to undergo one or both of flexural motion and vibration when the PMUT receives or transmits ultrasonic signals.