Search

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]

Recent learning-based intrinsic image decomposition methods have achieved remarkable progress. However, they usually require massive ground truth intrinsic images for supervised learning, which limits their applicability on real-world images since obtaining ground truth intrinsic decomposition for natural images is very challenging. In this paper, we present an unsupervised framework that is able to learn the decomposition effectively from a single natural image by training solely with the image itself. Our approach is built upon the observations that the reflectance of a natural image typically has high internal self-similarity of patches, and a convolutional generation network tends to boost the self-similarity of an image when trained for image reconstruction. Based on the observations, an unsupervised intrinsic decomposition network (UIDNet) consisting of two fully convolutional encoder-decoder sub-networks, i.e., reflectance prediction network (RPN) and shading prediction network (SPN), is devised to decompose an image into reflectance and shading by promoting the internal self-similarity of the reflectance component, in a way that jointly trains RPN and SPN to reproduce the given image. A novel loss function is also designed to make effective the training for intrinsic decomposition. Experimental results on three benchmark real-world datasets demonstrate the superiority of the proposed method. [ABSTRACT FROM AUTHOR]

Nowadays, the commonly used yarn tension sensors cannot meet the requirement well in the textile manufacturing process. So surface acoustic wave (SAW) yarn tension sensor is a good selection to adapt to today's textile manufacturing and improve the production efficiency. First, two key problems of SAW yarn tension sensor in practical application are proposed in this article, one is the construction of the sensor measurement system, the other is the temperature compensation. Then, the integrated design of measurement circuit and measurement structure is implemented and introduced in this article, which improves the accuracy, reliability, and sensitivity of SAW yarn tension sensor. Finally, binary regression analysis method and least squares support vector machine (LSSVM) algorithm optimized by particle swarm optimization (PSO-LSSVM) method are applied to the temperature compensation of SAW yarn tension sensor, which both achieve satisfactory compensation effect. By comparison, PSO-LSSVM method is more convenient and flexible, and still has a large space for improvement. Through those research contents, it can be concluded that the design and implementation of the measurement system lay a foundation for the practical application of SAW yarn tension sensor, the research of temperature compensation is of great significance to the wide application of the sensor. [ABSTRACT FROM AUTHOR]

This article describes the first-order perturbation analysis of nonlinear responses in surface acoustic wave (SAW) resonators on the LiTaO3/SiO2/Si structure, where bulk wave radiation is negligible near the main resonance while the longitudinal resonances are not. The coupling-of-modes (COMs) theory is employed as the platform for both the linear and nonlinear response analyses. Stress and dielectric flux are assumed to be generated by nonlinear mixture of linear strain and electric fields proportional to the SAW displacement and applied voltage, respectively, and they are newly introduced to the extended COM equations as excitation sources. The simulated third harmonic (H3) responses agree well with the experimental ones including that caused by longitudinal resonances, and effectiveness of the present method is demonstrated. Furthermore, this theory is applied to the infinitely long interdigital transducer (IDT) to highlight the impact of longitudinal resonances. [ABSTRACT FROM AUTHOR]

A LiNbO3 (LN)/SiO2/Si multilayered structure was recently reported as a new platform for achieving wideband radio frequency (RF) filters. However, the in-band ripples in filters resulting from the spurious Rayleigh mode lead to deteriorated performance, and thus, a wide Rayleigh elimination window (REW) is highly desired for realizing spurious-free wideband surface acoustic wave (SAW) filters with a wide design space and good process tolerance. Here, we investigated the spurious mode suppression on the LN/SiO2/Si platform theoretically and experimentally through modulating the cut angle ($\theta $) of LN. The ${K}^{{2}}$ dispersion characteristics of the main mode (shear-horizontal wave) and spurious mode (Rayleigh wave) on LN/SiO2/Si substrates were systematically analyzed by the finite-element method (FEM), along with bulk LN for comparison. It is found that the REW is wider on LN/SiO2/Si than bulk LN, as Rayleigh wave can be totally eliminated with Cu electrode normalized thickness (${h}_{\text {Cu}}/\lambda $) ranging from 0.1 to 0.19 when $\theta $ is between 19° and 22° on the LN/SiO2/Si platform, in contrast to the quite narrow REW on bulk LN restricted to some specific ${h}_{\text {Cu}}/\lambda$. To verify the simulation results, resonators were prepared on 15°YX-LN/SiO2/Si, 20°YX-LN/SiO2/Si, bulk 15°YX-LN, and bulk 20°YX-LN. In addition, the typical spurious-free wideband SAW filter with ${h}_{\text {Cu}} = {200}$ nm based on the 20°YX-LN/SiO2/Si platform demonstrates high performance with a center frequency (${f}_{\text {c}}$) of 1.27 GHz, a minimum insertion loss (ILmin) of 0.7 dB, and a 3-dB fractional bandwidth (FBW) of ~20.1%. This work provides a workable solution in fabricating spurious-free wideband and low-loss SAW filters for fifth-generation (5G) applications. [ABSTRACT FROM AUTHOR]

This work explores micromachined heterostructured waveguides that leverage strong interactions between acoustic phonons and electrons to enable radio frequency (RF) signal amplification or attenuation. A thin-film piezoelectric-on-semiconductor stack is tailored to generate high electromechanical coupling Lamb waves that are impacted by high mobility electrons within a microacoustic waveguide. Lamb waves are generated by RF signal via interdigital electrodes on the piezoelectric layer; by applying a voltage to the semiconductor layer so that the electrons lead mechanical waves, the RF signal is amplified through the acoustoelectric (AE) effect. Conversely, the signals propagating faster or in the opposite direction of the electron flow undergo attenuation, rendering the waveguide nonreciprocal. Research on the AE effect dates to the mid-20th century and until now has been mostly focused on surface acoustic waves (SAWs). In this work, enabled by high-quality bonded thin films of lithium niobate (LN) and silicon (Si), it is shown that fundamental symmetric ($S0$) Lamb mode waveguides at 100 s of MHz can achieve more than 40 dB of AE gain and strong nonreciprocal transmission with less than 10 mW of bias power consumption. This could enable implementation of switches, delay lines, isolators, and circulators, which are critical for interference cancellation and full-duplex radio. The AE effect is observed to be stronger in some higher $S0$ harmonics, allowing for scaling to higher frequencies with optimized electrodes that have more relaxed critical dimensions. In addition, up to 5.5-dB sustained terminal gain measured in this work implies the potential for transistor-less amplifiers that could be implemented in concert with more traditional acoustic devices in a single-chip manner. [ABSTRACT FROM AUTHOR]

In this study, a high-performance surface acoustic wave (SAW) device based on a multi-layer graphene amplifier is proposed, which is mainly composed of a zinc-oxide (ZnO) substrate, an interdigital transducer (IDT) input, a graphene sensing layer, metal electrodes and a fork finger transducer output. The sensor uses graphene’s unique band structure and the electron transport properties of the high mobility of the carrier with extremely small temperature influence to amplify the signal of the SAW caused by the sensing signal, thereby improving the sensitivity of the SAW sensor. The influence of graphene variable conductivity controlled by the uniform electric field on SAW amplifier devices in the near field is studied and analyzed. A small size surface acoustic wave device is fabricated with microelectromechanical system (MEMS) technology. The results show that the resonant frequency of the sensor is about 72 MHz, and the maximum amplification performance is 36 dB/cm. It is found that the SAW amplifier proposed in ZnO piezoelectric crystals exhibits superior performance in graphene-based SAW amplifiers. [ABSTRACT FROM AUTHOR]

The shear horizontal surface acoustic wave (SH-SAW) resonators with excellent quality factor and temperature stability were fabricated on 42°YX-LiTaO3/SiO2/sapphire substrate. For comparison, the 4-inch LiTaO3/SiO2/sapphire (fully insulating LiTaO3-on-insulator, FI-LTOI) and LiTaO3/SiO2/poly-Si/Si (trap-rich layer assisted LiTaO3-on-insulator, TR-LTOI) substrates are prepared by ion-cutting process. The GHz acoustic delay lines (ADLs) built on FI-LTOI exhibit a propagation loss of only 2.95 dB/mm, which is 37.5% smaller than the 4.72 dB/mm of the ADLs on TR-LTOI. The demonstrated SH-SAW resonators on FI-LTOI exhibit higher ${Q}$ -values than those on TR-LTOI. Among them, a FI-LTOI based resonator with the resonant frequency of 1.76 GHz exhibits a maximum Bode- ${Q}$ (${Q} _{{\mathrm {max}}}$) of 4,421, an effective electromechanical coupling coefficient of 13.34%, an excellent figure of merit of 589.8, and a well-compensated temperature coefficient of frequency of −9.1 ppm/°C. More importantly, the ${Q} _{{\mathrm {max}}}$ of the FI-LTOI based resonator is maintained well (2,791) even at 200 °C whereas that of the TR-LTOI based resonator decreased to 674. Overall, the FI-LTOI substrate may serve as an advanced material platform of SAW devices for 5G-FR1 bands. [ABSTRACT FROM AUTHOR]

The Radiofrequency (RF) industry needs surface acoustic wave (SAW) resonators with high-quality factors (${Q}$) and spurious-free response characteristics to also have steep roll-off and a flat passband. In this work, SAW resonators based on 36°YX-LiTaO $_{{3}} /$ SiO $_{{2}} /4\text{H}$ -SiC multilayer substrates are fabricated that can effectively suppress acoustic energy leakage. Finite element method (FEM) simulations show that the effective electromechanical coupling coefficient (${k}^{{2}}_{\text {eff}}$) of the multilayer structure SAW resonators can be improved by choosing SiO2 and 36°YX-LT layers of appropriate thickness, and it is the high acoustic velocity of the slow shear bulk wave in 4H-SiC that leads to the multilayer structure SAW resonators showing excellent performance in confining acoustic energy. However, from the slowness curve, we measure the power flow angle (PFA) to be 10°, which, if uncorrected, would lead to serious transverse modes between the resonant frequency (${f}_{\text {r}}$) and the antiresonant frequency $({f}_{\text {a}})$. To counter this, a multilayer structure SAW resonator with transverse mode suppression is fabricated using interdigital transducers (IDT) with a tilted angle of 10°. The multilayer resonator displays an extremely high Bode- ${Q}$ of over 3500 and a high impedance ratio of 85 dB. As predicted by the simulation results, ${k}^{{2}}_{\text {eff}}$ is up to 12%, and an extremely high figure of merit (FOM) of 423 is achieved. The enhanced performance of SAW resonators demonstrated in this work can open a door for constructing high-performance SAW filters with low insertion loss and high stability characteristics. [ABSTRACT FROM AUTHOR]

ScAlN/Si, a CMOS compatible material, was used to manufacture GHz operating surface acoustic wave devices, targeting manipulation and control of spin waves via SAW devices. A thin ScAlN piezoelectric layer was deposited on high resistivity (111) oriented Silicon and two port SAW devices were processed using advanced nanolithographic techniques. The Surface Acoustic Wave and Spin Wave coupling was performed via a thin magnetostrictive layer (Ni) placed between the SAWs interdigitated transducers. Both Rayleigh (4.67 GHz) and Sezawa (8.05 GHz) propagation modes could be observed. The amplitude of the S21 parameter around the two resonances was measured for values of the magnetic field $\mu _{0}\text{H}$ from −280 to +280 mT, at different angles ($\theta $) between the SAW propagation direction and the magnetic field direction. A maximum decrease of 2.54 dB occurred in S21 for the Rayleigh mode at $\mu _{\textbf {0}}\text{H}$ = −90 mT, and of 7.24 dB for the Sezawa mode at $\mu _{0}\text{H}$ = −203 mT, both at $\theta $ = 45°. These values were extracted from time gated processing of the frequency domain raw data. Nonreciprocity associated to the coupling was analyzed for the two propagation modes. [ABSTRACT FROM AUTHOR]

This article presents shear horizontal surface acoustic wave (SH-SAW) devices with excellent temperature stability and low loss on ultrathin Y42-cut lithium tantalate film on sapphire substrate (LiTaO3-on-sapphire, LTOS). The demonstrated resonators exhibit scalable resonances from 1.76 to 3.17 GHz, effective electromechanical coupling coefficients between 5.1% and 7.6%, and quality factors (Bode-Q) between 419 and 3019. The filter with a center frequency of 3.26 GHz features a suppressed spurious passband, a 3-dB fractional bandwidth (FBW) of 3%, and a minimum insertion loss (IL) of 2.39 dB. In addition, coplanar waveguides (CPWs) and SH-SAW resonators built on LTOS and LiTaO3-on-insulator (LTOI) substrates were compared over a temperature range of 25 °C–150 °C. Due to the extremely high resistivity of the sapphire and the excellent thermal stability of the LiTaO3/sapphire interface, the IL of the CPW and the impedance ratio (in addition to Bode-Q) of the SH-SAW on the LTOS are maintained well even at 150 °C, while those on the LTOI seriously deteriorate. Of these, the impedance attenuation of LTOS-SAW at the antiresonant frequency is only 3.7 dB at 150 °C, whereas that of LTOI-SAW reaches 9.6 dB, demonstrating excellent temperature stability of the LTOS substrate’s radio frequency (RF) performance. Overall, the SAW devices on LTOS substrates show great potential for temperature-sensitive and low-loss applications in RF wireless communications. [ABSTRACT FROM AUTHOR]

This research aims to overcome the tradeoff between bandwidth, temperature stability of frequency, and loss in surface acoustic wave filters. A novel multilayered structure, SiO2/Cu-grating/ $15^{\circ }~{Y}$ - ${X}$ LiNbO3/SiO2/sapphire, is proposed. Resonators based on the multilayered structure are studied theoretically and experimentally. The results show that the multilayered structure can sufficiently suppress leaky wave and spurious responses, which significantly degrade the performance of devices based on conventional SiO2/Cu-grating/ $15^{\circ }~{Y}$ - ${X}$ LiNbO3 structure. Fabricated resonators exhibit high performance including low frequency drift, large coupling, and large quality factor. A multilayered structure filter is designed, fabricated, and measured, resulting in a flat and clean passband with a small minimum insertion loss of only 1.01 dB. A large 3-dB fractional bandwidth of 14.74% is achieved, as well as a low temperature coefficient of frequency of approximately −18 ppm/°C. This research proposes a useful solution for high-performance filters in fifth-generation networks. [ABSTRACT FROM AUTHOR]

Objective: Separation and detection of micro-particles or cells from bio-samples by point-of-care (POC) systems are critical for biomedical and healthcare diagnostic applications. Among various microfluidic separation techniques, acoustophoresis-based technique has the advantages of label-free and good biocompatibility. However, most of the existing separation techniques are bulky and require additional equipment for analysis. Methods: We proposed a platform, which integrates an acoustophoresis-based separation device and a lensless imaging sensor into a compact standalone system to tackle this challenge. Standing Surface Acoustic Wave (SSAW) is utilized for label-free particle separation, while lensless imaging is employed for seamless particle detection and counting using self-developed dual-threshold motion detection algorithms. In particular, we specially optimized the design of microfluidic channel and interdigital transducers (IDTs) for higher performance bioparticle separation, designed a heat dissipation system for the suppression of fluid temperature, and proposed a novel frequency-temperature-curve based method to determine the appropriate signal driving frequency for IDTs. Results: At 2 μL/min flow rate, separation efficiency of 93.52% and purity of 94.29% for 15 μm microbead were achieved in mixed 5μm and 15μm microbead solution at a 25 dBm RF driving power, and similar results for mixed 10 μm and 15 μm microbead solution. Conclusions: The results showed that the integrated platform has an excellent capability to seamlessly separate, distinguish, and count microbeads of different sizes. Significance: Such a platform and the design methodologies offer a promising POC solution for label-free cell separation and detection in biomedical diagnostics. [ABSTRACT FROM AUTHOR]

The motivation of this work is to analyze the in-band intermodulation distortion (IMD) occurring in surface acoustic wave (SAW) devices, using a recently developed fast method based on the input–output equivalent sources (IOES). The method calculates the equivalent current sources of a given harmonic (H) or IMD, which when applied at the boundaries of any uniform nonlinear region produce the same nonlinearities as the full distributed circuit. The accuracy of the method is validated with a very simplified SAW resonator with ten digits, which is modeled by a discretized Mason-based circuit. The IOES method provides equal results to the ones obtained through harmonic balance (HB) simulations, performed by means of commercial software, being the first 1000 times faster. Once the accuracy of the method is guaranteed, it is used to analyze the measured in-band IMD3 of several lithium tantalite 42° cut leaky SAW (LSAW) resonators with different pitches and duty factors at the B66 long term evolution (LTE) frequency band. Those resonators are comprised of 100 and 20 electrode pairs for the active region and each of the reflectors, respectively, which implies the analysis of a very large distributed nonlinear problem with thousands of nonlinear local sources. The IOES method takes 35.4 s in simulating 51 frequency points, whereas this simulation is not possible using a commercial HB simulator on a general-purpose computer. [ABSTRACT FROM AUTHOR]

Multilayered structures extensively studied as a novel type of substrates for surface acoustic wave (SAW) devices are characterized by an asymmetry of wave propagation: acoustic wave characteristics generally change with inversion of propagation direction or interchange of top/bottom surfaces in one of the layers, though separately each material is symmetric for such inversions. In this article, the matrix formalism known as an effective tool for theoretical and numerical investigation of acoustic wave propagation in multilayered structures is applied to explain the existence of asymmetry and analyze its relation to the symmetry and orientations of combined materials. This phenomenon is illustrated by the examples of layered structures combining LiTaO3 (LT) plate with quartz or Si, previously reported as potential substrates for SAW devices with improved performance. Asymmetry arises from anisotropy of combined materials and occurs even when one of these materials is non-piezoelectric. It was estimated numerically as a variation of SAW resonator characteristics with substrate or plate inversion and was analyzed as a function of plate or substrate orientation. In particular, it was shown that “polarity inverted” structure enabling alternative resonator performance for the same material layers can be obtained either by an interchange of top/bottom surfaces of a piezoelectric plate or by inversion of propagation direction in a substrate. Asymmetry decreases with the introduction of an isotropic layer at the plate-substrate interface. [ABSTRACT FROM AUTHOR]

Fan-out wafer-level package (FOWLP) technology is an ideal scheme for the surface acoustic wave (SAW) filter packaging due to its potential to achieve extensive numbers of interconnects with standard pitches at any shrink pattern of the wafer. Nevertheless, predicting the wafer warpage in the processes timeline is an intractable but instructive issue. This article focuses on the evolution of the wafer warpage in different packaging processes and on ameliorating the warpage control scheme for the FOWLP with the (SAW) filters. Combined with the meso-mechanical model and the transversely isotropic model (TIM) of composite material, curing deformation is taken into account. Given the anisotropy coefficient thermal expansion (CTE) of the LiTaO3, experiments and simulations are performed to analyze the influence of the process, structure, and material effects on the warpage. In addition, a new experimental process is proposed to reduce the impact of significant mismatches with submillimeter dies. Compared with the theoretical simulations, a class of warpage tests performed are achieved consensus. Finally, the warpage of the 8-in wafer is controlled within 2 mm. [ABSTRACT FROM AUTHOR]

The excitation of surface acoustic waves (SAWs) on the surface of the ferroelectric film [barium strontium titanate (BST)] located on the dielectric substrate (silicon) was studied theoretically. We found that the most effective SAW excitation takes place when spontaneous polarization occurs in the film plane and the wave propagates along the direction adjacent to the direction of the spontaneous polarization vector. Based on a nonlinear model of phase transitions in solid BST solutions, the dependency of the material constants of piezo-effect equations on the misfit strain with a fixed concentration was obtained numerically. The effect of various misfit strains on SAW characteristics was studied for the film located on single-crystal silicon. It was shown that the effectiveness of SAW excitation increases as the misfit strain nears the boundary of phase transition. [ABSTRACT FROM AUTHOR]

The development of 5G has put forward a higher demand for filters, and the purpose of this work is fabricating surface acoustic wave (SAW) filters with excellent temperature stability and high power handling using LiTaO3/SiC bonded wafers. SAW resonators with different wavelengths are fabricated on LiTaO3/SiC, and LiTaO3/Si, bulk LiTaO3 as well. We evaluate these resonators, concluding that the bilayer substrates can enhance the performance. Subsequently, SAW filters are designed and fabricated. For the filters based on LiTaO3/SiC, the center frequency is around 2.62 GHz and the minimum insertion loss is 1.90 dB. The whole passband is flat and larger than 200 MHz, and the return loss is larger than 10 dB. SiC is more effective than Si in the enhancements of temperature stability and power handling. SiC reduces the temperature coefficient of the frequency at the left side of the passband to about half of that on LiTaO3/Si and one-sixth of that on bulk LiTaO3, and enlarges the peak power handling to 35.7 dBm. The time-to-failure of the filters on LiTaO3/SiC is 3.8 times as long as LiTaO3/Si and 11.3 times the level of bulk LiTaO3, when an input power of 30 dBm is applied ceaselessly. This work demonstrates the potential of SAW filters based on LiTaO3/SiC for RF filters in 5G. [2021-0233] [ABSTRACT FROM AUTHOR]

Solving the phase ambiguity problem is crucial to achieving a wide-range and high-precision measurement for the frequency-domain sampling (FDS)-based surface acoustic wave (SAW) delay-line sensor systems. This study proposes an improved phase estimation algorithm called dual-band phase estimation (DBPE) to solve the problem. By using DBPE, the SAW sensor system can obtain an extensive and alterable measuring range without further requirements for sensor design or transmitted signals. Thus, it can be widely used in various FDS-based SAW delay-line sensor systems. Monte Carlo simulations and temperature measuring experiments, based on a YZ-cut LiNbO3 SAW delay-line sensor and a switched frequency-stepped continuous wave (S-FSCW) reader, are performed to demonstrate the algorithm’s validity. The Monte Carlo simulations show that DBPE can effectively solve the phase ambiguity problem and has better performance than frequency estimation in measuring precision at a low signal-to-noise ratio (SNR). The temperature-sensing experiments show that DBPE has a good performance in measuring range and precision, serving as a phase ambiguity solver in the temperature sensor system. [ABSTRACT FROM AUTHOR]

Acoustic wave devices have great potential for integration with lab-on-chip highly efficient microfluidics. This article investigates Lamb wave-based unidirectional transducers for application in acoustic wave-driven microfluidic devices with high efficiency. The simulation of the unidirectional transducer is performed via the finite element analysis. The optimal cell design of the transducer is suggested according to the Lamb wave uneven excitation. In particular, we propose a sophisticated double-side IDT pattern to enhance Lamb wave transduction. The anti-symmetric ${A}_{{0}}$ mode implemented with double-side unidirectional transducers is determined and optimized for the microfluidic device application. The optimum Lamb wave-based devices are fabricated on a wafer of 128° YX LiNbO3 with a thickness of 300 $\mu \text{m}$ using an elaborate two-side lithography technique. The amplitude of Lamb waves excited from the unidirectional transducers are measured and confirmed the unidirectionality, accordingly. Thorough atomization and jetting experiments driven by the unidirectional transducer are presented. The results agree with the simulation and verify the efficiency of the proposed double-side patterned unidirectional transducers in microfluidic applications. [ABSTRACT FROM AUTHOR]

Surface acoustic wave (SAW) cavities have been widely applied as electronic bandpass filters, sensors, microfluidic tweezers, and, in recent years, as devices for coupling with quantum systems. Here we propose a novel method of analyzing acoustic Fabry–Pérot spectra, by analogy with optical cavities, to determine the free surface velocity and attenuation of SAW waves, as well as the reflection of interdigital transducers (IDTs), all of which are crucial design parameters. In our experiment, two-port SAW resonators, consisting of two IDTs laterally separated by a free surface cavity length, are used to generate SAWs on 128° Y-X lithium niobate that are trapped between the two IDTs which also act as Bragg reflectors. Resonant cavity peaks can be observed through the electrical ${S}_{{11}}$ (reflection) spectrum measured on one IDT. The free spectral range and linewidths of cavity peaks are then measured to obtain the free surface SAW velocity, SAW propagation attenuation coefficient, and IDT reflection phase and amplitude. Our method of analyzing Fabry–Pérot spectra provides an intuitive approach for determining key characteristics of SAW waves and cavities. [ABSTRACT FROM AUTHOR]

This article describes a new transverse edge structure with double busbar for surface acoustic wave (SAW) devices employing a 42°YX-lithium tantalate thin plate such as incredible high-performance (I.H.P.) SAW. This design offers good energy confinement and scattering loss suppression for a wide frequency range. First, preexisting transverse edge designs are reviewed, and their difficulties are pointed out using the dispersion relation for lateral SAW propagation. Then, numerical simulations are performed using the periodic 3-D finite-element method (FEM) powered by the hierarchical cascading technique, and effectiveness of the proposed structure is revealed. In addition, we also provide a possible solution to expand the frequency range giving well energy confinement and demonstrate effectiveness of manipulating the SAW slowness curve shape for transverse mode suppression. [ABSTRACT FROM AUTHOR]

In this article, a CMOS tunable channel-selection (CH-SEL) low-noise amplifier (LNA) with a feedforward (FF) $N$ -path filter and a gain- and phase-calibrated interference- cancellation technique is proposed for advanced front-end module (FEM)-less cellular transceivers. The proposed LNA exhibits a high- $Q$ RF bandpass/band-rejection filter characteristic based on a four-path filter, an active blocker cancellation with an FF translational loop, and an LC tank at the input, internal node, and output, respectively. The proposed gain- and phase-calibration block and tunable high-pass filter in the FF filtering path adjust the notch frequency corresponding to the transmitter leakage signal and help realize sharp notch filtering. The proposed CH-SEL LNA with CMOS duplexers compensates for the limited filtering performance of the CMOS duplexer and improves the blocker-tolerance and linearity of the receiver, and thus, can replace surface acoustic wave duplexers in the FEM. Fabricated in the 65-nm CMOS process, the CH-SEL LNA achieves a maximum voltage gain of 19.3 dB, minimum NF of 5.1 dB, and notch rejection ratio of more than 27.8 dB. It can also cover mid-band frequencies in the range of 1.35–2.7 GHz for 5G new radio cellular applications, exhibits an average current of 20 mA from a supply voltage of 1 V, and has an active die area of 1.16 mm2. [ABSTRACT FROM AUTHOR]

In this letter, a novel highly magnetostrictive ferromagnetic shape memory alloy (FSMA) interdigital transducers (IDTs) have been fabricated over AlN piezoelectric layer in the surface acoustic wave (SAW) resonator. The influence of an external magnetic field on the fabricated SAW device has been investigated in terms of device parameters such as resonance frequency (${f}_{R}$), frequency shift $\boldsymbol \Delta {f}_{R}/{f}_{R}$ (%) and electro-mechanical coupling coefficient (${K}^{{2}}$). A resonance frequency of ~2.258 GHz was observed at 0 Oe and a frequency shift ($\boldsymbol \Delta {f}_{R}) \sim {89}$ MHz occurs at 1350 Oe. The present device shows high tunability ($\boldsymbol \Delta {f}_{R}/{f}_{R}) \sim {3.9}$ %. It could be ascribed to the strain-induced giant $\boldsymbol \Delta \text{E}$ -effect in the highly magnetostrictive Ni-Mn-In layer at room temperature. The experimental results have been fitted with a modified Butterworth-Van Dyke (mBVD) circuit model to extract the equivalent circuit parameters in the absence and presence of the magnetic field. A maximum electromechanical coupling coefficient was calculated to be ~0.58, which decreases to 0.35 with the magnetic field. The fabricated SAW resonator displays a high sensitivity of ~0.66 Hz/nT. Such magnetostrictive FSMA IDTs based tunable SAW resonator could be a potential candidate for room temperature remote magnetic field sensors and multifunctional MEMS devices. [ABSTRACT FROM AUTHOR]

The detection of carbon dioxide (CO2) and water molecules (H2O) is of great interest because they play an important role in the fields of industry, agriculture, climate and medical treatment. However, both experimental studies and engineering applications indicate that most CO2 sensors suffer from selectivity problems in high humidity. Herein, we detect concentrations of CO2 and H2O simultaneously through decoupling surface density and shear modulus under negligible effect of electric conductivity based on a surface acoustic wave (SAW) resonator at 221 MHz. The SAW-based sensor demonstrates a small measurement error of ~ 65 ppm in CO2 and ~ 1.2% RH in H2O. The sensor also shows excellent short-term stability of 0.8 kHz. Besides, this general method that using a single SAW resonator to detect two analytes selectively will be useful for other resonator-based sensors. [ABSTRACT FROM AUTHOR]

Ultrasound is capable of noninvasive transcranial focusing and activating the targeted neurons in brain regions, receiving increasing attention. Ion channel, acting as a nano-ionic switch, enables to modulate the ion flow across cellular membranes and it is of importance to control the firing frequency of a neuron. In this article, we demonstrate the behavioral response of Caenorhabditis elegans (C. elegans) in response to ultrasound stimulation mediated by the activation of mechanical sensitive MEC-4 and MEC-6 ion channels. By specific mutation of MEC-4 and MEC-6 ion channels, mutant worms show a significant decrease in the percentage of reversal behavior (30% ± 10.5% and 10% ± 6.9%, respectively), compared with wild type (85% ± 8.2%). Furthermore, ALM and PLM neurons expressing MEC-4 and MEC-6 ion channels could be evoked directly by ultrasound stimulation, indicating MEC-4 and MEC-6 may pave a new way for sonogenetics. [ABSTRACT FROM AUTHOR]

Surface acoustic wave (SAW) devices are increasingly applied in life sciences, biology, and point-of-care applications due to their combined acoustofluidic sensing and actuating properties. Despite the advances in this field, there remain significant gaps in interfacing hardware and control strategies to facilitate system integration with high performance and low cost. In this work, we present a versatile and digitally controlled acoustofluidic platform by demonstrating key functions for biological assays such as droplet transportation and mixing using a closed-loop feedback control with image recognition. Moreover, we integrate optical detection by demonstrating in situ fluorescence sensing capabilities with a standard camera and digital filters, bypassing the need for expensive and complex optical setups. The Acousto-Pi setup is based on open-source Raspberry Pi hardware and 3-D printed housing, and the SAW devices are fabricated with piezoelectric thin films on a metallic substrate. The platform enables the control of droplet position and speed for sample processing (mixing and dilution of samples), as well as the control of temperature based on acousto-heating, offering embedded processing capability. It can be operated remotely while recording the measurements in cloud databases toward integrated in-field diagnostic applications such as disease outbreak control, mass healthcare screening, and food safety. [ABSTRACT FROM AUTHOR]

This article presents a thermal control design method for a surface acoustic wave (SAW) device. We designed a heat-dissipation structure and packaging scheme to solve three key issues observed in SAW devices using anisotropic crystals as piezoelectric substrates in acoustofluidics (e.g., lithium niobate): SAW chip cracking caused by thermal stress, SAW chip cracking caused by mismatched thermal expansion coefficients of the packaging materials, and enhancement of the structural strength and stability of the SAW chip. This study establishes the physical model of the designed structure and the relationship between the steady-state working temperature and the physical properties of the material. By comparing these physical properties and numerical calculations, we identified nanosilver adhesive as the most effective bonding material between the SAW chip and the heat sink. In addition to designing and fabricating, we also evaluated our SAW devices experimentally. The results not only confirmed that the abovementioned three key problems were solved but also demonstrated the significant enhancement of the stability of the SAW device. [ABSTRACT FROM AUTHOR]

This article presents design and implementation of switchable dual-band filters using surface acoustic wave (SAW) resonators and vanadium oxide (VO2) switches imbedded within the filter using both hybrid and monolithic integration. The switched dual-band filter has two channels and four switching states: transmission only of the lower channel, transmission only of the upper channel, transmission of both the channels, and no transmission. The experimental results are presented for the first switchable dual-band filter of order 5 with two discrete VO2 switches strategically integrated within the proposed filter’s structure using hybrid integration. The five-pole dual-band filter demonstrates a measured insertion loss of 3.7 and 3.9 dB in the transmission states at 765 and 935 MHz, respectively. To improve the overall performance of the proposed switched dual-band filter, a second seven-pole filter with six VO2 switches, three for each channel, is designed and fabricated. VO2 switches are monolithically integrated with SAW resonators on the same substrate using a four-mask in-house fabrication process. The article also presents experimental results to study the impact of the monolithically integrated VO2 switches on the linear and power-handling performance of SAW resonators. VO2 monolithically integrated switched dual-band filter has two channels at 600 and 725 MHz. It exhibits a measured insertion loss of 3.23 and 3.22 dB for the two channels. Depending on the number of detuned resonators in the OFF state for each channel, an isolation of 20–40 dB is demonstrated. The monolithic integration of VO2 switches results in improved performance of the filter along with significant size reduction. [ABSTRACT FROM AUTHOR]

This article presents spur reduction and efficiency enhancement techniques for pulse-modulated polar transmitters (PMPTs). The technique allows low-power out-of-band odd spurs in PMPTs to be suppressed deeply before going into power amplifiers (PAs). By configuring the PAs as a balanced Doherty amplifier for efficiency improvement with quad-phase aliasing-free digital pulsewidth modulation (PWM), the several even spurs can be separated directly into the isolation port of the output quadrature coupler. The residual even spurs can be easily suppressed using direct connection of an absorptive bandpass filter (BPF) behind each PA. Using the proposed architecture, the prototype transmitter achieved 49.4% drain efficiency at an output channel power of 28 dBm using 20-MHz bandwidth long-term evolution (LTE) 16-quadrature amplitude modulation (QAM) test signals at 836.5 MHz. After output signal restoration by the proposed absorptive filters, an output power level of 27.1 dBm and 40% drain efficiency were achieved while keeping the spur level close to −60 dBc without using any surface acoustic wave (SAW) filter. [ABSTRACT FROM AUTHOR]

A magnetic field sensor consisting of a surface acoustic wave (SAW) generator and a cantilever beam with NdFeB permanent magnets are developed. The working principle of this magnetic sensor relies on the center frequency shift of the SAW device under the magnetic field as a consequence of the torque-effect-induced deformation of the cantilever, which changes the stress on the piezoelectric LiNbO3 and the spacing between the interdigital transducers (IDTs). Compared with other magnetic sensors based on acoustic resonance, the performance of our proposed sensor is greatly enhanced due to the structural design by incorporating the magnetic torque effect. High sensitivity of 1277.69 kHz/Oe and a large percentage change in frequency of 5.177% are achieved in this magnetic sensor near a resonant frequency of 848 MHz. The proposed magnetic sensor based on SAW and torque effect exhibits great potential for applications in magnetic field detection. [ABSTRACT FROM AUTHOR]

In this letter we investigate phonon-dominated mobilities for carriers in a diamond field effect transistor with a cubic Boron Nitride (cBN) overlayer. We investigate the intra-subband scattering due to interaction of electrons with acoustic phonons, treated properly as quantized surface acoustic Rayleigh waves, and include, for the first time, the interaction with remote polar phonons originating in the cBN overlayer. We conclude that the surface acoustic phonon scattering is the dominant mechanism limiting the mobility of electrons for temperatures below 375 K. [ABSTRACT FROM AUTHOR]

We investigate a hybrid treatment—consisting of an atmospheric pressure plasma pretreatment, followed by an MHz surface acoustic waves (SAWs) treatment with either de-ionized (DI) water or plasma activated water (PAW)—on mung beans to accelerate the germination process, as mung bean sprout is one of the important food staples. For the early growth rate (after 320 min), we observe that the hybrid treatment with PAW can lead to approximately 217% higher moisture content for the treated beans when compared with that without hybrid treatment. Additionally, the hybrid-treated beans germinate in around 120 min, while the untreated beans germinate only in around 420 min, that is, 3.5-fold faster for treated beans. This can be attributed to the dominant effect of SAW that accelerates stage 1 water absorption process and the effect of direct plasma and PAW that promote stage 2 metabolism process, leading to the enhancement in stage 3 germination process in early growth rate. For the post growth rate (after 24 h), we observe that the hybrid treatment with DI water can lead to an approximately 44.20% in higher moisture and 71.17% in radicle length when compared with untreated beans. Interestingly, the hybrid treatment with PAW, on the other hand, is observed to have an adverse effect on germination after 24 h, that is, approximately 14.51% lower in moisture content and 43.49% lower in radicle length for the hybrid-treated beans with PAW when compared with that with DI water. [ABSTRACT FROM AUTHOR]

A wedge transducer is developed using poly-phenylene-sulfide (PPS) as an exciter of high-intensity surface acoustic wave (SAW) to remove droplets adhering to automobiles’ front shield glass. Since the front shield glass has a glass/rubber/glass triple-layered configuration, SAW is needed to be employed to confine the vibration energy within the first glass layer and avoid the energy absorption in the rubber layer. PPS is chosen among popular engineering polymers for the vibrating body because its attenuation at ultrasonic frequency is lower than other polymer materials. To assess the feasibility of our proposal, we designed and fabricated a PPS wedge transducer, and investigated the vibration characteristics and the capability to remove droplets. The transducer, which incorporated a lead-zirconate-titanate (PZT) plate and a PPS wedge, had the total volume of $24\times 20\times8.5$ mm3. At the voltage of 24.8 V, a SAW having the wavelength of 2 mm and the vibration velocity of 14.5 mm/s was excited on the glass plate, and the droplets were removed with the SAW. [ABSTRACT FROM AUTHOR]

LiNbO3 (LN) or LiTaO3 (LT) thin plates bonded to quartz are novel types of layered substrates for temperature-compensated surface acoustic wave (TCSAW) devices. In SAW resonators with Al electrodes arranged on LT/quartz and LN/quartz substrates, improved temperature behavior due to opposite signs of temperature coefficients of frequency (TCF) in quartz substrates and LT or LN plates can be combined with high ${Q}$ -factors if the quartz orientation is optimized. The quartz orientation areas that enabled high ${Q}$ -factors were deduced from analyzing the quartz anisotropy and the characteristics of shear horizontally (SH) polarized waves were calculated in the optimal orientations as functions of the quartz cut angle and plate thickness. The simulation results illustrated by contour plots of the wave characteristics revealed the presence of zero lines on the plots demonstrating TCFs at resonant (TCFR) and antiresonant (TCFA) frequencies in both layered structures. The strong quartz anisotropy explained anomalous temperature behavior of SAW resonators and the existence of LT/quartz structures with TCFA = TCFR facilitating the design of SAW devices with improved thermal stability in the passband. In the LT/quartz structures, two TCFs vanished simultaneously at certain plate thickness and quartz orientation, while in the LN/quartz zero lines did not intersect but low TCF = −(10–20) ppm/°C combined with electromechanical coupling exceeding 18% were obtained numerically in some structures. The effect of inverting the propagation direction or cut angle in one of the combined materials on the wave characteristics was discussed and numerically estimated. [ABSTRACT FROM AUTHOR]

This paper describes a new type of electrowetting (EW)-driven digital microfluidic (DMF) platform incorporated with an acoustic bubble for improving the viscous droplet mixing performance on an open surface. First, it is experimentally verified that the working principle of the two different actuation methods: EW-driven droplet actuation on an open surface and acoustically driven bubble excitation in an aqueous medium, respectively. Then, it is investigated that the acoustic excitation of the bubble injected into the droplet. When an acoustically excited bubble inside the droplet generates microstreaming at the natural frequency of the bubble, the microstreaming inside the droplet is visualized using fluorescent particles and a high-speed camera. To examine the effect of the microstreaming inside the droplet on mixing performance, the mixture droplet consisting of safranin and glycerol (60 wt%) is used in this experiment. The mixing efficiency is measured through the mixing index calculated by image analysis. The mixture droplet with an acoustically excited bubble is completely mixed within 40 seconds owing to the microstreaming generated by the acoustically oscillating bubble at its natural frequency. On the other hand, the same mixture droplet with only a diffusion process remains unmixed for more than 5 mins. The transportation of a droplet ($10~\mu \text{l}$) containing a bubble ($800~\mu \text{m}$ in diameter) and the removal of the bubble from the droplet are demonstrated using an EW chip. Finally, as a proof of concept, the manipulation of droplets with the enhanced mixing performance on the proposed digital microfluidic platform is demonstrated by the combination of EW droplet actuation and acoustic bubble excitation. [2021-0057] [ABSTRACT FROM AUTHOR]

This article presents a high quality factor (${Q}$) load sensor based on Sc0.2Al0.8N/aluminum nitride (AlN)-on-silicon surface acoustic wave (SAW) resonator. Finite element method (FEM) analysis is performed to predict the resonance frequency and the wave propagation mode. A high- ${Q}$ of 7200 at the parallel resonance frequency (${f}_{p}$) of 447.50 MHz is measured for Sc0.2Al0.8N/AlN configured SAW resonator on a silicon substrate. Experimental values for variation of series resonance frequency (${\Delta } {f}_{s}$) and variation of ${f}_{p}$ (${\Delta } {f}_{p}$) are found to be −75.3 and −186.8 kHz with variation of applied force $({\Delta } \textit {F)} = 4.155$ N, operating in the analyzed range. The linear approximation of measured frequency variations under force is ${\Delta } {f}_{s}/{F} = -12.7$ kHz/N and ${\Delta } {f}_{p}/{F} = -46.2$ kHz/N. Moreover, the force sensitivities for this sensor are −28.4 and −103.2 ppm/N for ${f}_{s}$ and ${f}_{p}$ , respectively. This high- ${Q}$ scandium-doped AlN (ScAlN)/AlN-based SAW resonator exhibits high sensitivity, demonstrating that the structure can be used as load sensors in industrial applications such as manufacturing, medical, grocery, and automotive industries. [ABSTRACT FROM AUTHOR]

Theoretical study of the effect of uniaxial pressure on the propagation characteristics of plate modes as Lamb and SH waves in a lithium niobate plate is carried out. A change in the effective crystalline symmetry, as well as the effective elastic constants under the pressure influence, has been derived. The controlling coefficients describing the pressure influence on the plate modes’ phase velocities are calculated for the various applications of uniaxial pressure. The uniaxial pressure influence on the hybridization of the elastic waves is discussed. [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]

To identify buried assets, this article presents a novel design of surface acoustic wave (SAW) tag to enhance its underground penetration capacity. A penetration depth model for a SAW tag buried in materials is established to investigate the depth of detection and guide the design of the SAW tag. Multipulse position with all reflectors in two groups (MPP-ART) coding scheme is proposed to reduce the insertion loss of the SAW chip. A novel embedded monopole microstrip tag antenna is investigated with a stable frequency performance when embedded in diverse types of materials. Furthermore, a linear frequency modulation pulse compression transceiver based on software defined radio is implemented to enhance the penetration depth. The insertion loss of the SAW chip at 920 MHz with the MPP-ART coding scheme, is reduced to 26.58 dB. Through experiments, the penetration depth of the SAW radio frequency identification prototype has reached 0.75 m in river water, 0.8 m in tap water, 1.5 m in wet sand, and 3 m in dry sand, respectively. The experimental results demonstrate that the SAW tag can work in various materials with good penetration depth, relatively immune to electromagnetic interference with adjacent metallic objects, making it suitable for the identification of buried assets for industrial applications. [ABSTRACT FROM AUTHOR]

An increasing demand for surface acoustic wave filters with high performances contributes to the necessity of reducing sizes and costs. The present work proposes a multilayered structure of high-velocity layer/SiO2/interdigital transducers (IDTs)/piezoelectric-single-crystal substrate to further validate the strengths of packageless devices. Resonators based on the SiNx/SiO2/IDTs(Cu)/15°Y-X LiNbO3 structure are simulated and analyzed. One-port resonators are designed, fabricated and tested on the basis of the simulation, and results validates the feasibility of no encapsulation. Finally, by using this multilayered structure, a packageless filter with a center frequency of 2.14 GHz and an ultra-small size of 0.695 × 0.490 × 0.122 mm3 is successfully designed and realized, maintaining well-balanced performances. This work has demonstrated the strengths of packageless devices which can be obtained by utilizing the proposed multilayered structure, and may promote the development of device miniaturization. [2021–0035] [ABSTRACT FROM AUTHOR]

This article develops a novel theoretical and modeling approach for a surface acoustic wave (SAW) acoustoelectric amplifier applicable to thin-film overlay resistive or semiconductor material that is within or outside the acoustic path. The theory is developed for a direct-coupled SAW and a thin-film resistive interaction layer. The analysis uses the combination of coupling of modes and charge control analysis to develop a complete model describing the small-signal operation and the large-signal saturation effect. The model is developed for the case of direct coupling of thin films in the propagation path or coupling electrodes either inside or outside the propagation path. The approach describes the phenomenological physics and amplifier’s key parameters. Predictions are compared to previously published experimental results on lithium niobate using a monolayer graphene film that yielded continuous-wave operation and a net terminal gain. [ABSTRACT FROM AUTHOR]

In this article, near-zero drift and high electromechanical coupling acoustic resonators have been designed and demonstrated. The acoustic resonator is based on Lamb acoustic waves in a bimorph composed of lithium niobate on silicon dioxide. Our approach breaks through a performance boundary in conventional Lamb-wave resonators by introducing the bimorph while operating at higher order resonant modes. This enables the resonator to achieve frequency scalability, a low-temperature coefficient of frequency, and high electromechanical coupling altogether. The electromechanical coupling and temperature coefficient of the resonator were analytically optimized for the A3 mode through adjusting the thicknesses of different materials in the bimorph. Resonators with different dimensions and stack thickness were fabricated and measured, resulting in a temperature coefficient of frequency ranging from −17.6 to −1.1 ppm/°C, high electromechanical coupling ranging from 13.4% to 18%, and quality factors up to 800 at 3.5 GHz. The achieved specifications are adequate for fifth-generation (5G) sub-6-GHz frequency bands n77 and n78. [ABSTRACT FROM AUTHOR]

The rapid development of the fifth-generation (5G) wireless system is driving strong demand for high-performance radio frequency filters. This work studies shear horizontal surface acoustic wave (SAW) devices using 15°-rotated Y-cut X-propagating (15°Y-X) LiNbO3/SiO2/SiC multilayered substrates. Single-crystalline 15°Y-X LiNbO3 films are bonded to SiO2/SiC handling substrates by the smart cut technology. On the basis of accurate finite-element-method simulations, LiNbO3/SiO2/SiC wafer configurations are optimized to suppress spurious resonance due to Rayleigh-mode and transverse-mode responses, and one-port resonators with a clean spectrum, a high electromechanical coupling coefficient of 22.00%, and an admittance ratio (impedance ratio) over 65 dB are successfully implemented. Based on the characteristics of the resonators, high-performance filters with a center frequency of 1.28 GHz, a large 3-dB fractional bandwidth of 16.65%, and a low minimum insertion loss of 1.02 dB are successfully designed and fabricated. Furthermore, no ripples in the passband of the filters are observed. Additionally, the filters exhibit a temperature coefficient of center frequency of −63.8 ppm/°C and a large power durability of 33.2 dBm. This work confirms the high performances of the SAW devices using the 15°Y-X LiNbO3/SiO2/SiC multilayered substrate, and this type of SAW device exhibits a prospect of commercial applications in the 5G wireless system. [ABSTRACT FROM AUTHOR]

In wireless network applications, such as routing decision, network selection, etc., the Multi-Attribute Decision Making (MADM) is widely used. The MADM approach can address the multi-objective decision making issues effectively. However, when the parameters vary greatly, the traditional MADM algorithm is not effective anymore. To solve this problem, in this paper, we propose the pairwise-based MADM algorithm. In the PMADM, only two nodes’ utilities are calculated and compared at each time. The PMADM algorithm is much more accurate than the traditional MADM algorithm. Moreover, we also prove that the PMADM algorithm is sensitive to the parameters which vary seriously and insensitive to the parameters which change slightly. This property is better than that of the traditional MADM algorithm. Additionally, the PMADM algorithm is more stable than traditional MADM algorithm. For reducing the computational complexity of the PMADM algorithm, we propose the low-complexity PMADM algorithm. For analyzing the computational complexity of the l PMADM algorithm, we propose the tree-based decomposing algorithm in this paper. The l PMADM algorithm has the same properties and performances as that of the PMADM algorithm; however, it is simpler than the PMADM algorithm. The simulation results show that the PMADM and l PMADM algorithms are much more effective than the traditional MADM algorithm. [ABSTRACT FROM AUTHOR]

The surface acoustic wave (SAW) humidity sensor may possess many attractive sensing characteristics such as high sensitivity, high resolution, high stability, frequency output, ease of interfacing, small size, and broad dynamic range. Mostly, the polymer materials are used for the SAW humidity sensor fabrication. But the polymer SAW sensors suffer from broad bandwidth, instability due to ambient temperature, nonlinearity, and small dynamic range. This article presents the fabrication of metal oxide film humidity sensors using SAW resonators of 433.92-MHz frequency. Five different SAW humidity sensors were fabricated by varying the deposited alumina film thickness to measure humidity in the range of 0%–98% relative humidity (RH). The hydrophilic films were formed by dip coating of alumina solution of different molar concentrations. The alumina film is thermally stable and inert. The static and dynamic response characteristics were determined from the shift in resonant peaks at different humidity using an HP 85046A vector network analyzer (VNA). The minimum sensitivity of the least sensitive sensor was found to be 2.51 kHz/%RH. The sensors show linear response ($R^{2} \ge0.98$), high sensitivity (max. ~ 9 kHz/%RH), negligible hysteresis error (≤0.50%), wide dynamic range, and inexpensive fabrication due to the use of commercial resonators. The response parameters of the sensors were compared with the parameters of other oxide SAW sensors reported in the literature. Finally, the linear sensor was interfaced to the electronic and associated signal conditioning circuits to display humidity in %RH. [ABSTRACT FROM AUTHOR]

The rapid growth of the advanced consumer 5G wireless mobile phones has propelled the demands of fabricating surface acoustic wave (SAW) filters with smaller size and high performance. Three-dimension wafer-level package (3-D WLP) for SAW filter is a promising solution to replace conventional surface mounted technology and chip-scale packaging. In this article, a new WLP for SAW filter with a size of 1.3 mm × 1.1 mm × 0.35 mm is developed using thin dry film capping. The new 3-D WLP significantly reduces the overall thickness which is particularly meaningful for low-profile smartphones and tablets. A number of key processes were developed. To improve the quality, finite element modeling (FEM) is used to simulate the mechanical stress to optimize cavity structure. Reliability tests were performed and the results indicated that there were no significant frequency response changes occurred and low insertion loss (IL) in pass band was less than 0.2 dB after pro-conditional level 3 test, unbiased highly accelerated stress (uHAST) test, and temperature cycling (TC) test on SAW filter packages. It can be concluded that 3-D WLP for SAW filter achieves miniaturization, good electrical performance, and reliability. [ABSTRACT FROM AUTHOR]

Surface acoustic wave (SAW) sensors with ferromagnetic materials are used to measure magnetic fields or electric currents. The magnetic field sensitivities of SAW magnetic field sensors are essentially influenced by various factors. The sensing mechanism is complex due to the multiphysics coupling of the magnetic field, solid mechanics, and electric field. The magnetostriction effect, $\Delta E$ effect, and the third-order material constants are taken into consideration. The shape demagnetizing effect is reduced by increasing the length-to-width ratio and length-to-height ratio of a ferromagnetic film on an SAW resonator. The model is verified by experiments and accurately predicts the magnetic field sensitivities of SAW resonant magnetic field sensors. The factors affecting the sensitivities are investigated from the perspective of the sensing mechanism. A grooved sensing surface structure is explored for improved sensitivity. The results are beneficial to design reliable SAW magnetic field sensors with enhanced sensitivity. [ABSTRACT FROM AUTHOR]

In this work, we present the first group of gigahertz low-loss, wideband, and high power handling delay lines (ADLs) using a thin-film lithium niobate (LiNbO3)-on-sapphire platform. The ADLs leverage a single-phase unidirectional transducer (SPUDT) to efficiently excite the shear horizontal surface acoustic wave (SH-SAW) in the film stack. The fabricated miniature SH-SAW ADL at 1.1 GHz shows a low insertion loss (IL) of 2.8 dB, a wide fractional bandwidth (FBW) of 6.14%, and a fast phase velocity of 5127 m/s. The device also features a high 1-dB compression point (P1dB) of 30.4 dBm. The temperature coefficient of frequency is −45 ppm/K. ADLs with delays between 12 and 172 ns have been implemented, with IL between 2.8 and 8.3 dB. SH-SAW propagation characteristics are extracted, showing a group velocity of 4747 m/s and a propagation loss of 6.73 dB/mm or 31.9 dB/ $\mu \text{s}$. The simultaneous low-loss and high power handling illustrate the great potential of LiNbO3-on-sapphire for RF and cross domain applications at gigahertz. [ABSTRACT FROM AUTHOR]