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Improving measurement accuracy is the core issue with surface acoustic wave (SAW) micro-force sensors. An electrode transducer can stimulate not only the SAW but also the bulk acoustic wave (BAW). A portion of the BAW can be picked up by the receiving transducer, leading to an unwanted or spurious signal. This can harm the device's frequency response characteristics, thereby potentially reducing the precision of the micro-force sensor's measurements. This paper examines the influence of anisotropy on wave propagation, and it also performs a phase-matching analysis between interdigital transducers (IDTs) and bulk waves. Two solutions are shown to reduce the influence of BAW for SAW micro sensors, which are arranged with acoustic absorbers at the ends of the substrate and in grooving in the piezoelectric substrate. Three different types of sensors were manufactured, and the test results showed that the sidelobes of the SAW micro-force sensor could be effectively inhibited (3.32 dB), thereby enhancing the sensitivity and performance of sensor detection. The SAW micro-force sensor manufactured using the new process was tested and the following results were obtained: the center frequency was 59.83 MHz, the fractional bandwidth was 1.33%, the range was 0–1000 mN, the linearity was 1.02%, the hysteresis was 0.59%, the repeatability was 1.11%, and the accuracy was 1.34%. [ABSTRACT FROM AUTHOR]

Improving measurement accuracy is the core issue with surface acoustic wave (SAW) micro-force sensors. An electrode transducer can stimulate not only the SAW but also the bulk acoustic wave (BAW). A portion of the BAW can be picked up by the receiving transducer, leading to an unwanted or spurious signal. This can harm the device’s frequency response characteristics, thereby potentially reducing the precision of the micro-force sensor’s measurements. This paper examines the influence of anisotropy on wave propagation, and it also performs a phase-matching analysis between interdigital transducers (IDTs) and bulk waves. Two solutions are shown to reduce the influence of BAW for SAW micro sensors, which are arranged with acoustic absorbers at the ends of the substrate and in grooving in the piezoelectric substrate. Three different types of sensors were manufactured, and the test results showed that the sidelobes of the SAW micro-force sensor could be effectively inhibited (3.32 dB), thereby enhancing the sensitivity and performance of sensor detection. The SAW micro-force sensor manufactured using the new process was tested and the following results were obtained: the center frequency was 59.83 MHz, the fractional bandwidth was 1.33%, the range was 0–1000 mN, the linearity was 1.02%, the hysteresis was 0.59%, the repeatability was 1.11%, and the accuracy was 1.34%.

This article proposes an approach using surface acoustic wave (SAW) device to decrease passband ripples and sidelobes as two key problems of wavelet transform processors (WTPs). The passband ripples are primarily generated through electrode reflections and transducer end-effects. The proposed method uses unbalanced split-electrode interdigital transducers (IDTs) to prevent electrode reflections. The problem of transducer end-effects is alleviated by attaching SAW absorbers to both ends of the substrate edge, which can effectively absorb the spurious SAW arriving at the edges of the piezoelectric substrate. Moreover, because the radiation energy of bulk acoustic wave (BAW) has a sidelobe distribution, the greater sidelobes are predominantly caused by the BAW radiation. This problem is alleviated by engraving bidirectional slots on the substrate at the back of the WTPs of the unbalanced split-electrode IDTs to suppress the BAW radiation. The experimental results demonstrate that the passband ripples and sidelobes of the WTPs decrease to 0.72 and 6.58 dB, respectively. [ABSTRACT FROM AUTHOR]

This work presents the complete synthesis procedure and circuit transformations needed to go from the characteristic polynomials to the transversal network formed by electroacoustic resonators. This filter topology allows the possibility to achieve any filter response in spite of limited electroacoustic coupling. This is crucial for obtaining very wideband filters with arbitrary positions of transmission zeros. Additional circuit transformations reveal the flexibility of such topology to control other important parameters of the acoustic filter such as the impedance of the resonators and their resonant frequencies, which directly affect the manufacturing process. The transversal topology for electroacoustic filters has been verified by the synthesis, design, fabrication, and measurement of a very wideband filter to meet the requirements of 5G N77 frequency band, centered at 3.75 GHz with 910 MHz of bandwidth. [ABSTRACT FROM AUTHOR]

This article describes derivation of an equivalent circuit for nonlinear responses in film bulk acoustic resonators from the first-order perturbation analysis using the piezoelectric constitutive equations with the ${h}$ -form. For simplicity, electrodes and piezoelectric layers are considered as mass and spring, respectively, in the derivation. Then, it is demonstrated that the second- and third-order harmonic responses can be simulated well by the circuit. In addition, nonlinearity in the Si substrate is also taken into account and its impact is discussed. It is also discussed how the frequency dependences vary with the nonlinearity mechanisms as a finding from the derived equivalent circuit. [ABSTRACT FROM AUTHOR]

This paper investigates the applicability of acoustic wave devices using an interdigital transducer placed on a thin piezoelectric crystal plate to the 3–5-GHz range, where significant performance degradation was expected in surface acoustic wave (SAW) devices. Three types of the SAW-like devices were fabricated by using a KrF stepper/scanner, and their performances are compared from various aspects: 1) a 3.5-GHz resonator using a rotated $Y$ -cut LiTaO3 plate attached on a Si substrate; 2) a 5-GHz resonator using a $X$ -cut LiNbO3 plate on a Si substrate; and 3) a 5.4-GHz $A_{1}$ Lamb mode resonator on a free-standing $Z$ -cut LiNbO3 plate. It is revealed that these devices offer excellent performances even in the 3–5-GHz range. [ABSTRACT FROM AUTHOR]

In this letter, we present simulation and measurement results of a novel structure to suppress transverse modes in radio frequency temperature-compensated surface acoustic wave (TC-SAW) resonators and filters. We propose a bent TC-SAW resonator structure to suppress such transverse modes which in general trapped between the busbars, based on the fact that higher TC-SAW wave modes in the resonator suffer higher loss at the resonator boundary. The higher wave modes leak energy out from the resonator busbars after multiple bounces along the length of the resonator. By adding this structure to our existing transverse mode suppression technique, we successfully suppress the bulk of the transverse modes in the resonators and filters. To test the effectiveness of the proposed structure, we fabricate the bent resonators and filters in a standard TC-SAW fabrication process on 128YX lithium niobate (128YX-LN) substrate. The measured long-term evolution band 39 filter response shows the effectiveness of this structure in suppressing transverse modes. [ABSTRACT FROM AUTHOR]

In this paper, we present the bulk acoustic wave (BAW), the sound–electricity reclamation (SER), and the insertion loss as the three key problems of a wavelet transform processor using surface acoustic wave devices. The solutions to these problems are achieved in this study. The more the number of electrode pairs for the interdigital transducer (IDT) is, the weaker the excited BAW is, so the BAW can be eliminated when the number of electrode pairs for IDT is large enough. The substrate material of a small electromechanical coupling coefficient (ECC) k^2 and the low-impedance load of IDT can eliminate SER. When the output ends of the wavelet transform processors are respectively connected to the amplifiers, their insertion losses can be compensated. X\-112^0Y\ \LiTaO3 (small ECC k^2) is used as a substrate material to fabricate the wavelet transform processor. [ABSTRACT FROM PUBLISHER]