Considering the new requirements for multiple frequencies and high integration in RF front-end devices for future mobile communication, this study examines a novel laterally excited Lamb wave resonator that exhibits both SAW and FBAR technical characteristics.The structure design, parameter optimization, and preparation method for a C-band laterally excited bulk acoustic resonator (XBAR) based on a c-axis optimally oriented aluminum nitride piezoelectric film are proposed, and the process is validated.Two XBAR samples with spurious mitigation were fabricated using lift-off and ICP-RIE, achieving a resonant frequency of 4.464 GHz, a quality factor of 3 039, and an f×Q product of 1.56×1013 GHz in a footprint smaller than 0.12 mm2 .The application potential of the prepared resonators in an RF filter was simulated and analyzed.This study provides an effective design and process technology support for the further development of multi-frequency and highly integrated miniaturized filter modules.

Owing to its high electromechanical coupling coefficient (k2eff>30%), the horizontal shear (SH) acoustic modes in lithium niobate (LN) single-crystal films are typically investigated to develop thin-film acoustic resonators with large electromechanical coupling and ultra-wideband acoustic filters. However, its temperature coefficient of frequency (TCF) is extremely high (>-50×10-6/℃). A high TCF not only reduces the effective bandwidth but also limits the power-management capability of the filters. Herein, we present an investigation into the optimization design of a low drift, large electromechanical coupling horizontal-shear surface acoustic wave (SH-SAW) resonator based on the X-cut LN/SiO2/Si structure using a three-dimensional periodic finite-element model. Simulation results show that when the SH-SAW propagation angle ψ is between -10° and -20°, the film thicknesses of LN and SiO2 are 0.1λ and 0.2λ (where λ is the period of the interdigital transducer) respectively, the metallization rate of the aluminum electrode (η) is 0.4, the relative thickness of the electrode is between 5% and 10%, the k2eff of the SH-SAW resonator remains at ~30%, and the TCF is less than -20×10-6/℃. Hence, the resonator is suitable for developing the next generation of low-temperature drift, ultra-wideband 5G SAW filters.

With rapid development in mobile technology, film bulk acoustic resonators have developed in a high frequency and wide bandwidth direction.This study focuses on the technological process of back cavity etching and a lateral exciting film bulk acoustic resonator on the POI (LiNbO3/SiO2/Si).On the study of the IDT optical lithography, etching and back cavity corrosion, the critical process parameters are determined.The frequency response curve shows that resonance and antiresonance frequencies were 4 565 and 5 035 MHz, respectively.The effective electromechanical coupling coefficient was 20.86%, which is significant for research on high frequency and wide bandwidth film bulk acoustic resonators.

A shunt-capacitance-type ladder-type topology was proposed by adding a shunt capacitance in a ladder-type topology to further reduce the insertion loss of a narrow-band filter. The shunt capacitance was used to modify the anti-resonant frequency of the resonator for reducing the bandwidth of the filter with sacrificing low insertion loss. A narrow-band temperature compensated SAW (TCSAW) filter with low insertion loss based on a SiO2/Cu/127°YX-LiNbO3 structure was developed successfully via resonator design and evolutionary algorithm optimization. The experimental results indicate that the center frequency of the filter, relative bandwidth, and passband insertion loss are 1 514 MHz, 0.46%, and only 1.45 dB,respectively. Further, the attenuation at the frequency 20 MHz outside the passband decreases to 24 dB, remote out-of-band attenuation is greater than 30 dB, attenuation at the WiFi band is up to 48 dB, TCF is -20×10-6/℃, and the size of the device is 1.1 mm×0.9 mm.

In this study, the velocity change mode of a transversely coupled ultra-narrow band surface acoustic wave filter is analyzed using the waveguide method.The changes in the central coupling strip structure and coupling distance of the transversely coupled surface acoustic wave filter are modeled and calculated using the multi-physics COMSOL software, and the frequency response characteristics are analyzed.An ultra-narrow band SAW filter with frequency of 898.144 MHz and insertion loss of 6 dB has been designed and verified.The results show that the fractional bandwidth of surface acoustic wave filter using the center coupled bar with an open cavity reaches 7.2‰, which is 2‰ higher than that of the non-open cavity structure of 5.2‰.This indicates that the change of the center coupled bar structure of a transversely coupled surface acoustic wave filter can change the fractional bandwidth of ultra-narrow band surface acoustic wave filters.

This study investigates the accurate temperature sensitivity calculation of surface acoustic wave (SAW) filters with arbitrary complex membrane structures and circuit topologies at different temperatures.The temperature field is coupled with the acoustic/electrical equation in the form of thermal stress and strain, considering the electromagnetic factor of the package model.Combining the hierarchical cascade algorithm and full-wave simulation technology, the temperature sensitivity of SAW filters in this specific contextis calculated.In addition, the frequency response characteristic, TCF value, insertion loss, bandwidth and rejection of the SAW filter under different temperatures are comprehensively analyzed.Based on the design of a SAW filter with 41°Y-X LiNbO3/SiO2/Si~~poly/Si(111), the results are in good agreement with the experimental results, and the effectiveness and feasibility of the proposed method are verified.

Microfluidic temperature distribution on a non-piezoelectric substrate is studied using Lamb waves with 1 MHz excitation frequency in piezoelectric ceramics.Theoretical analysis demonstrates that the acoustothermal effect is induced by the Lamb waves radiating longitudinal waves into the fluid and viscous friction loss.An infrared camera observes the thermal distribution of droplets from Lamb wave excitation to a steady-state temperature.The droplet temperature on the Lamb wave radiation side is higher than that of other areas, and the high temperature area tends to spread to the top.Regarding the acoustothermal phenomena of droplets with different liquid viscosities, the temperature distribution of an oil droplet is more uniform and exhibits weaker dynamic behavior.Finite element analysis of the acoustic flow and thermal effect demonstrate that the droplet high temperature diffusion trend corresponds to the maximum acoustic flow inside the droplet.

Miniaturization and high-frequency quartz resonators are being developed, with increasingly smaller sizes.Therefore, it is very important to develop a low-cost precision manufacturing process for quartz resonators.Etching experiments on quartz wafers were conducted to determine the optimal process conditions for precise manufacturing of rectangular resonators.The effects of temperature on the integrity of the metal protective layer and of etching time on the surface roughness of quartz were studied.The corrosion rate was stable and moderate, which was conducive to the precise manufacturing of the resonator.The process flow of the quartz resonator was designed to obtain an ultra-thin rectangular AT-cut high-frequency quartz resonator with good quality.The causes of the error were analyzed, and a set of wet etching process with good precision was summarized.It is expected that the thickness of the rectangular resonator will be reduced to 10 μm or less using low-cost means.

A JGD-type single-crystal laser furnace produced by China Electronics Technology Chip Research Institute is a single-crystal furnace with automatic diameter control for upward weighing, which helps realize fully automatic intelligent growth control of crystal-pulling methods. The JGD Czochralski crystal furnace control software uses a mathematical model for Czochralski crystal growth. The entire process of crystal growth is based on the mathematical model, and real-time closed-loop feedback control is achieved using a crystal weight as the control variable. This software employsfour-segment and arbitrary multi-segment crystal mathematical models. The former model embodies the concept of smooth transition between the seed crystal, shoulder, and equal-diameter segments in the design of the shoulder segment, and the latter model is more flexible and diverse in curve design, making crystal mathematical model design more convenient. The crystal mathematical model of the JGD single-crystal furnace control software is widely used in various crystal growth processes including those of InSb, YAG, and other crystals. The crystal shape is well controlled and of excellent quality.

As a passive, small-sized, and high-power-tolerant device, the film bulk acoustic resonator (FBAR) has been widely used in radio frequency signal processing.Wafer-level hermetic packaging represents miniaturized packaging and plays a critical role in various high-reliability applications.Both gold-gold and gold-tin bonding are widely used in FBAR hermetic wafer-level packaging.However, gold-tin bonding has a more straight forward implementation process.Therefore, this study investigates the application of gold-tin bonding in hermetic wafer-level packaging.Under the condition of ensuring bonding strength, 3 GHz filter samples were produced.The experimental results demonstrated identical perfomances with all samples passing the reliability tests.

This article introduces an acousto-optic modulator, with six channels, that achieves parallel and independent modulation of six laser beams by preparing electrode arrays on the transducer, designing independent impedance matching circuits and electrical input interfaces, and integrating six acousto-optic interaction units.The acousto-optic modulator has an optical wavelength of 355 nm, a working frequency of 220 MHz, a diffraction efficiency of over 75% for each channel, and a global cross-talk below 0.5%.

The miniaturization of oven-controlled crystal oscillators (OCXO) is necessary for developing communication technology. When developing a small-sized OCXO, we found that frequency curves of the OCXO leaned upwards uniformly when ambient temperature increased from -40 to 85 ℃, failing to satisfy the requirement of ±3×10-9. Variations in the heating current of the oscillator with temperature cause biasing voltage fluctuations in the variable diode when current flows through the ground pin made of metal with low conductivity. This problem was solved using the proposed dual ground pin and passive compensation methods.

Pb(Zr1-xTix)O3 ceramics were prepared using the traditional solid-state method.The temperature stability was enhanced by adjusting the zirconium titanium mole ratio to locate these materials within the tetragonal region, and the electrical properties were improved by optimizing the sintering temperature.Experimental results showed that the system entered the monotetragonal region when x=0.52, and the temperature stability of the ceramics was subsequently improved.Over the range from room temperature to 300 ℃, the d33 change rate was ±14.7%. The Pb(Zr0.48Ti0.52)O3 ceramics sintered at 1 250 ℃ exhibited optimal electrical properties: d33=183 pC/N, TC=402 ℃, and εr=1 209.

In this study, a self-powered synchronous asymmetric voltage flip and charge extraction (SP-SAFCE) circuit is designed.The circuit combines the features of parallel synchronized switch harvesting on inductor and synchronous electric charge extraction to achieve a function that completely flips the voltage polarity at positive peaks and completely extracts charge at negative peaks.Compared with conventional piezoelectric interface circuits, the SP-SAFCE circuit has the advantages of a self-powered peak detection module and switch, no rectifier bridge, and no requirement of impedance matching.Comparison experiments are conducted under varying conditions of driving frequency and distance between magnets.It is proved that under the same shock excitations, the SP-SAFCE circuit operates at a voltage 0.8 V lower than that of the synchronous electric charge extraction circuit, and its output power is approximately 1.15 times that of the synchronous charge electric extraction circuit, which makes it suitable for use as the interface circuit for a piezoelectric harvester under shock excitations.

In this study, multimodal acquisition and bandwidth broadening are enhanced by employing multimodal spread spectrum theory to establish a versatile piezoelectric vibration-energy acquisition system. The system comprises two modules-an energy collector and a power-management circuit. The collector operates across four resonant frequencies, thus ensuring efficient energy harvesting in low-frequency vibration settings. The power-management circuit converts AC power into stable DC power for charging energy-storage components. Following modal-harmony response analysis, an experimental platform is constructed for system testing. Experimental results indicate an operational frequency band of 16.1 to 27.8 Hz, with a peak output voltage of 33.75 V under a simple harmonic force and an acceleration of 6 m/s2. Upon impedance matching, the optimal resistance value is shown to be 200 kΩ, which results in an output power of 115.85 μW.

This paper introduces a multi-directional miniature piezoelectric vibration energy collection device with a zigzag shape, which is surrounded by a square frame with a size of 34 mm × 2 mm × 1 mm, and its internal structure consists of four asymmetric combined cantilever beams.The main cantilever beam is fixed on the inner wall of the frame and is perpendicular to the z direction, whereas the secondary cantilever beam is connected to the end mass block of the main cantilever beam.In this study, first, the dynamic model of a composite cantilever beam vibration system under basic excitation is established.Subsequently, through a finite element simulation, the influence of different stiffness and mass values on the displacement amplitude is analyzed and compared, the vibration characteristics of the composite cantilever beam system are verified, and the optimal structural parameters are determined.When the thickness of the primary and secondary cantilever beams is 0.3 mm, the optimal inertial mass of the primary and secondary mass blocks is 619.32 and 342.3 g.The simulation calculation shows that the collectable electric power in the z direction is 3.138 5 mW, and the collectable power in the x and y directions is 0.720 5 mW.Finally, an experimental platform of a miniature energy collector is built, and in actual testing, the output power in the z direction is 2.85 mW, the output power in the x, y direction is 0.57 mW.

Piezoelectric stack actuators are widely used for driving intelligent deformation devices.Piezoelectric stacks have small displacement outputs, which can be increased using amplification structures.To this end, an elliptical displacement amplification structure was designed in this study, and the effect of structural parameters on the performance of displacement amplification structure was analyzed. The structural parameters include the major axis of the ellipse, thickness of the shell, displacement in the X direction, and width of the piezoelectric stack. The performance factors include displacement output, stress intensity, and amplification factor in the Y direction. The samples were fabricated based on the optimization results, and an amplification factor of approximately 5.3 was achieved. The transient response of the amplification structure driven by the high-frequency voltage was analyzed, and the influence of the frequency of driving signal on the displacement output was simulated.The results showed that the displacement output of the structure did not exhibit distortion driven by a alternating voltage with a period of 0.01 s.

A noncontact ultrasonic dental cleaning device is designed in this study. It addresses the limitation of a transducer’s acoustic transmitting power due to the space in the oral cavity by combining 12 ultrasonic horn units in parallel to form a braces-type array structure. Results of acoustic-structural coupling finite-element simulation and regression analysis show that the piezoelectric-phase type is PZT-5H, which features a hollow conical ultrasonic horn in the acoustic-permeable module. The average acoustic power radiated to the dental surface is 2.32 W, and the minimum positive-and negative-phase acoustic pressures are 794.668 and -800.854 kPa, respectively, between 300 and 400 kHz. The acoustic field encompassing the entire dentition can be generated by sweeping frequency cleaning in this frequency band. Finally, the device can achieve complete supercavitation and noncontact dental cleaning.

Silicon-on-insulator high-temperature pressure sensors can operate at temperatures above 125 °C due to their unique properties.Generally, the resistance forming the Wheatstone bridge is located solely in the pressure-sensitive region to enhance its sensitivity.However, during its operation, a certain height difference exists between the resistance of the heavily doped region of the pressure sensor device and its connection with the metal lead.The thermal stress in this area increases under high-temperature conditions during pressurization and electrification.Metal leads cannot meet the high-temperature requirements and may break or fail due to overheating.Therefore, this study investigated a silicon lead technology that had the same layer height as a varistor.A metal lead was laid flat on this silicon lead, and the end was annealed to form a robust ohmic contact.Experimental testing demonstrated that this method could ensure the normal operation of the pressure sensor in a high-temperature environment of 300 °C.The metal lead was well connected to the resistance zone.The stress in the sensitive area of the sensor was reduced by nearly 50%, and the optimized sensor sensitivity met the design requirements.

This study presents the design of a high-isolation ultra-wideband (UWB) four-element multiple input multiple output (MIMO) antenna with a single notched band.The dimensions for this antenna are 65 mm×65 mm×0.8 mm.The four slot antenna units are placed horizontally and orthogonally, and the antenna is fed by a coplanar waveguide, facilitating ease of manufacture and integration.The defect ground and cross isolation branches are used for decoupling.Furthermore, a U-shaped slot is etched on the antenna radiation patch to create a notched band at 4.35-6.08 GHz, which effectively suppresses WLAN communication interference (5.15-5.825 GHz).The measured operating band of the proposed antenna is 2.46-10.6 GHz, with an isolation level of less than -20 dB.The notched band is generated at 4.35-6.08 GHz, which effectively suppresses the WLAN interference.Additionally, the envelope correlation coefficient is maintained below 0.02, and the diversity gain exceeds 9.998.The measured performance is robust, demonstrating significant potential for extensive application in UWB-MIMO communication systems.

In this study, a novel wideband near-coupled millimeter-wave microstrip array antenna is proposed, specifically designed for 77-81 GHz medium- and long-range automotive radar applications.The antenna array comprises a microstrip line and series of rectangular and polygonal radiation units.These units are periodically distributed on both sides of the microstrip line and separated by approximately half of the guiding wavelength.The rectangular and polygonal radiation elements are designed to enhance excitation coupling.In addition, the impedance bandwidth is widened and out-of-band frequency is suppressed.Different radiation elements and rectangular reflection slots are matched to achieve the beam shaping effect and realize a flat shoulder radiation pattern.The normalized resistance of the radiation unit is controlled by adjusting the interval between the radiation unit and microstrip line.At the operating frequency range of 77-81 GHz, the gain of the array antenna exceeds 14 dBi, and the impedance bandwidth reaches 7.47%(76.5-82.4 GHz).An actual example was processed and tested, and the accuracy of the design was confirmed by simulations and actual measurements.

The PLL phase stabilization principle was theoretically analyzed to solve the problem of phase difference stability between multi-channel singular frequency signals. Further, a multi-channel singular-frequency phase difference stabilization algorithm was proposed to solve the greatest common divisor between frequencies and simultaneously output frequencies to meet the requirements of phase difference stability.The testing results indicate that phase difference stabilities are less than 4° when the output frequencies are in the S-band,satisfying the requirements while effectively verifying the feasibility and flexibility of the algorithm.

The conventional atomic force microscope (AFM) and critical-dimension atomic force microscope (CD-AFM) probes are limited by the low effective scanning height of the tip, which prevents the accurate scanning and imaging of deep trenches and large overhanging sidewall structures. Hence, a design and preparation scheme for a new CD-AFM probe with a large-aspect-ratio tip structure is proposed herein. The developed CD-AFM probe has an effective tip height of 5.1-5.8 μm and an aspect ratio of 14. The improved effective height is approximately four times that of conventional silicon-based CD-AFM probes. Finally, the developed probe isevaluated using a deep-trench sample with a nominal depth of 2.3 μm and an aspect ratio of 4.6.

The aerospace honeycomb sandwich structure has a harsh service environment, and it is necessary to develop the corresponding structural health monitoring technology to ensure the safe operation of the structure.Debonding damage is difficult to monitor because it occurs in the internal adhesive layer.In this study, a distributed optical fiber sensor embedded in the adhesive layer is used to monitor the debonding damage of the honeycomb sandwich structure.In the embedded damage-monitoring test, the use of high-strength optical fibers and shallow boundary grooves improves the survival efficiency of the sensor and obtains the characteristics of the debonding damage strain.Using parametric modeling, a large number of finite element simulations were conducted at different damage locations.After adding white noise, 13 500 sets of data containing debonding damage characteristics were acquired.Substituting the simulated data into a convolutional neural network for training, the trained network achieved an accuracy of 98.84% in identifying the experimental damage data.In the current study, this method can identify 20 mm2 debonding damage, with an average positioning error of less than 4 mm.

High-intensity focused ultrasound (HIFU) transducers are a core component of focused ultrasound ablation surgery (FUAS) systems, whose electric impedance spectrum is an important index to determine working parameters that significantly affect FUAS systems performance.Real-time online monitoring of this spectrum is significantly beneficial.In this study, based on pulse response time-domain measurement, by merging the detected pulse signal serial into the FUAS operational electric driving signal sequence of the HIFU transducer, a real-time online monitoring system for the electric impedance spectrum of the HIFU transducer was constructed on the LabVIEW platform.Highly reproducible accurate measurements towards the magnitude and phase spectrum of the HIFU transducer electric impedance were achieved.Subsequently, a monitoring system was applied to determine dynamic changes in the electric impedance of the HIFU transducer under extreme working conditions.These include long-time service, high electrical driving power and duty cycle.The results demonstrate that the proposed system accurately monitors the HIFU transducer eigen frequencies drift, alongside nonlinear changes in impedance magnitude and phase.This paper presents a technical solution for real-time online monitoring of HIFU transducer impedance during FUAS, and provides feedback for drive parameter adjustment, which has practical application value for HIFU transducer design optimization and energy loss mechanisms.