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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]

Coupling of multiphysics including electrodynamics, elastodynamics, magnetodynamics, and electromagnetic (EM) radiation is involved in the operating process of bulk acoustic wave (BAW) antenna. There is still no good way to design the structure and evaluate the performance of the antenna in theory. Therefore, the multiphysics dynamic coupling model of the antenna is constructed by uniting Newton’s equation for acoustic wave, Maxwell’s equation for EM wave, and Landau–Lifshitz–Gilbert (LLG) equation for spin wave with constitutive relations of multiferroic materials to discuss the dispersion law of permeability and magnetomechanical coupling factor for the magnetostrictive layer. The importance of consistency between ferromagnetic resonance (FMR) frequency and BAW resonant frequency is demonstrated. The analysis shows that both increasing the anisotropic field or the saturation magnetization and decreasing the FMR linewidth are beneficial to improving the internal energy conversion efficiency and the average radiated power for BAW antenna. In addition, a micromagnetic module is introduced into finite element analysis (FEA) software to simulate the precession of unit magnetic moment at different frequencies. Thus, the analytical model is verified from the perspective of power absorption. [ABSTRACT FROM AUTHOR]

With the introduction of the working principle of coupled resonators, the coupled bulk acoustic wave (BAW) Micro-Electro-Mechanical System (MEMS) resonators have been attracting much attention. In this paper, coupled BAW MEMS resonators are discussed, including the coupling theory, the actuation and sensing theory, the transduction mechanism, and the applications. BAW MEMS resonators normally exhibit two types of vibration modes: lateral (in-plane) modes and flexural (out-of-plane) modes. Compared to flexural modes, lateral modes exhibit a higher stiffness with a higher operating frequency, resulting in a lower internal loss. Also, the lateral mode has a higher Q factor, as the fluid damping imposes less influence on the in-plane motion. The coupled BAW MEMS resonators in these two vibration modes are investigated in this work and their applications for sensing, timing, and frequency reference are also presented. [ABSTRACT FROM AUTHOR]

A 20-GHz fractional- ${N}$ analog phase-locked loop (PLL) leveraging a novel high-speed charge pump (CP) and an on-chip frequency reference is demonstrated. An on-chip fully integrable 2.5-GHz frequency reference using Texas Instrument’s indigenous bulk acoustic wave (BAW) resonator is demonstrated. The low noise high-frequency reference allows for significant lowering of the division modulus leading to enhanced suppression of CP, phase-frequency detector (PFD), and loop-filter (LF) noise. A low noise class-C transformer-coupled voltage-controlled oscillator (VCO) further allows for excellent jitter performance over wide integration bandwidths (BWs) while still working with a nominally low PLL loop BW. Capability is built into the design to characterize the PLL with either BAW or external reference. The design is implemented and fabricated in the GlobalFoundries 22-nm fully depleted silicon on insulator (FD-SOI) process. The class-C VCO is measured to be centered at $\sim $ 19.7 GHz with 16% tuning range (TR) while maintaining a flat $\vert {\rm FOM}\vert \sim $ 188 dBc/Hz (10-MHz offset) over the entire TR. The PLL measures an excellent jitter and $\vert {\rm FOM}_{j}\vert $ of 65/92 fs and $\sim $ 249/245 dB in integer/fractional modes, respectively. [ABSTRACT FROM AUTHOR]

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A nonlinear circuit model has been developed to model electrostriction in thin-film ferroelectric bulk acoustic wave (BAW) resonators. This new model is based on nonlinear coupling relations among strain, stress, electric field, and polarization, derived from the Landau–Devonshire theory. The coupling relations and the mechanical vibrations are then represented as lumped circuit elements using an improved approximation procedure along with an enhanced model for dielectric loss. The response from the simulation is compared with the measurement results obtained for a barium strontium titanate (BST) thin-film bulk acoustic resonator (FBAR) at different dc bias levels. The improved approximation procedure enables one to achieve accurate simulation results with reduced circuit model complexity. [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]

The conductive magnetic film will produce eddy current loss when it works in a high-frequency band, which will reduce the performance of bulk acoustic wave magnetoelectric (BAW ME) devices. If the eddy current loss is not taken into account in the devices modeling, the models will be seriously distorted. Therefore, combining the Maxwell’s equations with constitutive relations of ME material, we define the eddy current loss angle as a figure of merit to evaluate the eddy current loss. Then the models of eddy current loss rate of the potential energy and average radiated power are constructed, respectively. The finite element analysis is used to further validate the analytic model. In addition, the effect of isolation layers on eddy current suppression is studied by using the analytical model. The results show that the analytical solutions match with the numerical simulation results perfectly. [ABSTRACT FROM AUTHOR]

This work presents a new method to analyze weak distributed nonlinear (NL) effects, with a focus on the generation of harmonics (H) and intermodulation products (IMD) in bulk acoustic wave (BAW) resonators and filters composed of them. The method consists of finding equivalent current sources [input–output equivalent sources (IOES)] at the H or IMD frequencies of interest that are applied to the boundary nodes of any layer that can contribute to the nonlinearities according to its local NL constitutive equations. The new methodology is compared with the harmonic balance (HB) analysis, by means of a commercial tool, of a discretized NL Mason model, which is the most used model for NL BAW resonators. While the computation time is drastically reduced, the results are fully identical. For the simulation of a seventh-order filter, the IOES method is around 700 times faster than the HB simulations. [ABSTRACT FROM AUTHOR]

Acoustic wave (AW) filters for next-generation wireless communication systems are designed to prevent signal interference and to be as small as possible. Using a pole-zero extraction method with a ladder-type AW filter, this paper proposes an algorithm to optimize the parameters for each AW resonator. The pole-zero positions of the equivalent circuit model are aligned with those of a Chebyshev or elliptic filter in the s-domain in order to give a frequency response that satisfies the system requirements in terms of insertion loss, out-band attenuation, and selectivity. The optimized parameters produce a system that has the minimum number of resonators to fulfill the filter performance specifications, with reduced manufacturing cost, which occupies a smaller area. Finally, the system is validated using a simulation with a LTE Band3 Rx elliptic filter and the parameters for an equivalent modified Butterworth-Van Dyke model (mBVD) for each resonator.

With the introduction of the working principle of coupled resonators, the coupled bulk acoustic wave (BAW) Micro-Electro-Mechanical System (MEMS) resonators have been attracting much attention. In this paper, coupled BAW MEMS resonators are discussed, including the coupling theory, the actuation and sensing theory, the transduction mechanism, and the applications. BAW MEMS resonators normally exhibit two types of vibration modes: lateral (in-plane) modes and flexural (out-of-plane) modes. Compared to flexural modes, lateral modes exhibit a higher stiffness with a higher operating frequency, resulting in a lower internal loss. Also, the lateral mode has a higher Q factor, as the fluid damping imposes less influence on the in-plane motion. The coupled BAW MEMS resonators in these two vibration modes are investigated in this work and their applications for sensing, timing, and frequency reference are also presented.

Implantable medical devices have been facing the severe challenge of wireless communication for a long time. Acoustically actuated magnetoelectric (ME) transducer antennas have attracted lots of attention due to their miniaturization, high radiation efficiency and easy integration. Here, we fully demonstrate the possibility of using only one bulk acoustic wave (BAW) actuated ME transducer antenna (BAW ME antenna) for communication by describing the correspondence between the BAW ME antenna and components of the traditional transmitter in detail. Specifically, we first demonstrate that the signal could be modulated by applying a direct current (DC) magnetic bias and exciting different resonance modes of the BAW ME antenna with frequencies ranging from medium frequency (MF) (1.5 MHz) to medium frequency (UHF) (2 GHz). Then, two methods of adjusting the radiation power of the BAW ME antenna are proposed to realize signal amplification, including increasing the input voltage and using higher order resonance. Finally, a method based on electromagnetic (EM) perturbation is presented to simulate the transmission process of the BAW ME antenna via the finite element analysis (FEA) model. The simulation results match the radiation pattern of magnetic dipoles perfectly, which verifies both the model and our purpose.

We have developed a highly tunable film bulk acoustic wave resonator (TFBAR) using magnetostrictive (MS) Fe65Co35 thin films in acoustic layer stack. The resonator acoustic layer stack consists of Pt/ZnO/Fe65Co35 layers to tune the devices. Due to $\Delta {E}$ effect, TFBAR resonance frequency was up-shifted ~106.9 MHz (4.91%) in the presence of 2-kOe magnetic field. From experimental measurement, $\Delta {E}$ enhancement was estimated to be ~35 GPa. Further, it is observed that return loss (${S}_{{11}}$), phase response, and quality factor were improved in the presence of magnetic field. This improvement is due to the field-induced stiffness in the magnetic layer. Equivalent-modified Butterworth–Van Dyke (mBVD) circuit model was developed and fit with the experimental data, and circuit parameters were extracted. The proposed resonator is compact, low loss, power efficient, and highly tunable. This method also facilitates a new method of tuning FBAR devices using MS thin films. [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 article discusses on the measured third-order intermodulation (IMD3) products and third harmonics (H3) appearing in a set of six different solidly mounted resonators (SMR) and bulk acoustic-wave (BAW) resonators with different shapes and stack configurations. The discussion is supported by a comprehensive nonlinear distributed circuit model that considers the nonlinear effects potentially occurring in any layer of the resonator stack. The aluminum-nitride (AlN) and silicon-dioxide (SiO2) layers are identified as the most significant contributors to the IMD3 and H3. The frequency profile of the third-order spurious signals also reveals that, in temperature-compensated resonators, where the SiO2 layers are usually thicker, the remixing effects from the second-order nonlinear terms are the major contributors to the IMD3 and H3. These second-order terms are those that explain the second-harmonic (H2) generation, whose measurements are also reported in this article. Unique values of the nonlinear material constants can explain all the measurements despite the resonators have different shapes, resonance frequencies, and stack configurations. [ABSTRACT FROM AUTHOR]

This paper describes the realization of a miniaturized magnetic field sensor that is based on a film bulk acoustic resonator (FBAR) and works at ∼0.87952 GHz resonant frequency. The sensor has a multilayer stack of Si/SiO 2 /Pt/ZnO/Fe 65 Co 35 thin films with Fe 65 Co 35 as a magnetic field sensing layer and zinc oxide (ZnO) as a piezoelectric actuation layer. The influence of an externally applied magnetic field (0–1992 Oe) has been investigated in terms of resonance frequency shift due to ΔE-effect. High magnetostrictive composition Fe 65 Co 35 (65/35) was utilized for the optimal sensing response. The MFBAR resonator series resonance frequency (fs), parallel resonance frequency (fp), electromechanical coupling coefficient (K t 2), quality factor (Q), and figure of merit (FOM) were obtained 0.87952 GHz, 0.88252 GHz, 0.84%, 740.74 and 6.21, respectively. The magnetic sensor shows enhanced sensitivity (S) of 0.357 kHz/Oe with outstanding performance at high frequency and large magnetic field range (0–1992 Oe). A modified Butterworth-Van Dyke (mBVD) equivalent circuit model was developed and circuit parameters are extracted. The mBVD model provides insights into changes in the electrical behavior of the device when the sensor is exposed to a range of magnetic fields. This investigation represents a new kind of magnetic field sensor that is miniaturized, power efficient, high sensitivity, and very useful for low-field sensing applications in the limited space regime. [Display omitted] • ZnO based Film Bulk Acoustic Resonator (FBAR) as magnetic field sensor using Iron-Cobalt magnetostrictive material has been simulated, fabricated, characterised and investigated. • The die size of acoustic resonator is 1.0 mm × 1.0 mm × 0.3 mm (L×W×T) and the resonant frequency is 0.87952 GHz. • Iron-Cobalt magnetostrictive material is used as a magnetic sensing layer. • The magnetic sensor is investigated in the magnetic field range from 0 O to 1992 Oe based on ΔE effect. • The resultant magnetic sensor sensitivity (S) is 0.357 kHz/Oe. [ABSTRACT FROM AUTHOR]

In this paper, a micromachined differential pressure sensor based on force frequency effect in AT-cut quartz bulk acoustic wave resonators for vacuum measurements is presented. The frequency shift arising from the stresses generated in the quartz due to force application is known as the force frequency effect. Pressure is sensed by monitoring the shifts in the thickness shear mode resonance frequency of AT-cut quartz resonator due to the application of differential pressure across the micromachined quartz diaphragm. The sensors exhibit a large dynamic range of 1 mTorr–100 Torr with a resolution of ~1 mTorr (in the medium vacuum regime). A parametric study has also been carried out to study the effect of resonator thickness and diameter on sensitivity. It was found that the sensor’s response to pressure is extremely sensitive to mechanical boundary conditions, which results in performance characteristics such as dependence on the direction of the applied pressure and unexpected scaling with the diaphragm radius. [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 work, the non-linearities of a 3G/UMTS geared BandPass Bulk Acoustic Wave ladder filter composed of five resonators were modeled using non-linear modified Butterworth-Van Dyke model. The non-linear characteristics were measured and simulated, and they were compared and found to be fairly identical. The filter's central frequency is 2.12 GHz, the corresponding bandwidth is 61.55 MHz, and the quality factor is 34.55.

We study the effects of medium rotation on bulk acoustic wave (BAW) propagation. For a theoretical analysis of the BAW propagation characteristics, a motion equation for the plane harmonic waves propagating orthogonal to the rotation axis of the propagation medium was analytically resolved. We found that during medium rotation, the polarization of the waves becomes elliptical with the ratio of the polarization ellipse axes explicitly proportional to the angular velocity of the medium rotation, thereby opening the way for the design of sensitive elements (SE) for perspective angular motion sensors (AMS). Next, an analytical dependence of the SE informative parameter on the Poisson’s ratio of the acoustic duct material was obtained. The rotation effect on the dispersion of BAW propagation velocity was studied. Two approaches to the perspective SE design were proposed. An experimental study of a specially designed test assembly and SE model demonstrated high correlation with theoretical predictions and provided an estimate of a potential SE. Therefore, we believe that the study of acoustic wave propagation under nonclassical conditions is a promising direction for prospective solid-state AMS on based on BAW polarization effects design.

ABSTRACT The advances in semiconductor fabrication technologies have enabled the integration of Lamb-wave resonator on silicon substrate. But such integration has led to additional parasitic effects to the Lamb-wave resonators. The availability of an efficient equivalent-circuit model is thus vital. This paper proposes a modified hybrid π-type/Butterworth-Van Dyke (PiBVD) model. Compared with the conventional PiBVD model, the modified PiBVD model accounts for the parasitic inductances of the bonding wires. It therefore provides better accuracy when characterizing Lamb-wave resonators over a wide frequency range. Experiment results have also verified that the modified PiBVD model has better fitting on Y11 (input reflection factor in Y-parameter matrix). This improvement is greatly beneficial for resonator analysis and circuit designs © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:703-706, 2017 [ABSTRACT FROM AUTHOR]

The manipulation and focusing of submicron/nanometre-scale objects are becoming increasingly important in the fields of biology, chemistry, and materials science. Acoustofluidics provides for the high throughput and precise manipulation of cells and particles with simple equipment. However, application to submicron/nanoparticles is challenging due to the particle volume dependence of the acoustic radiation force and the relatively larger effect of the viscous drag force on small objects. Here, we present an acoustofluidic device that can focus submicron/nanoparticles, bacterial cells, and extracellular vesicles (EVs) using a high-frequency two-dimensional acoustic standing wave. We fabricate 50 µm × 50 µm square cross-section channels as acoustic resonators and generate a two-dimensional acoustic standing wave at an actuation frequency of 14.9 MHz. This configuration enables a strong acoustic radiation force towards the centre of the microchannel and a cross-section-centred single-vortex stream that does not counteract the acoustic radiation force. Using this device, polystyrene beads ranging in diameter from 50 to 500 nm were focused toward the channel centre, where a focused bead stream width of less than 5 µm was achieved at a flow rate of 3 µL min−1 for 100 nm beads and 9 µL min−1 for 200 nm beads. Furthermore, bacterial cells were successfully focused at a flow rate of 40 µL min−1, and the focusing of EVs was also demonstrated. Our acoustofluidic device can become a promising tool for a wide range of biological analyses targeting submicron cells, viruses, and EVs. • 50 µm ✕ 50 µm cross-sectional microchannel for 2D bulk acoustic (BAW) by 14.9 MHz of actuation frequency. • Applicable for focusing of bacterial cells and extracellular vesicles (EVs). • Tight focusing of submicron/nanoparticles at the centre by strong acoustic radiation force and a cross-section centred single-vortex stream. • Focusing of submicron/nanoparticles under various flow condition. [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, the principles of finite-element modeling for the electroacoustic simulation of bulk-acoustic-wave devices will be summarized. We will outline the model setup including governing equations and boundary conditions, as well as its efficient computer implementation. Particular emphasis will be given to tailoring the model dimension to the specific requirements of the desired investigation. As 3-D simulations still require a major effort, it will be illustrated that various aspects of device physics and design can already be addressed by fast and efficient 2-D simulations. Multiple theoretical and experimental evidence will be presented to demonstrate the validity of the modeling concepts. Based on various examples, it will be sketched how to benefit from numerical simulations for understanding fundamental effects, designing devices for actual products, and exploring novel technologies. [ABSTRACT FROM AUTHOR]

In this work, the non-linearities of a 3G/UMTS geared BandPass Bulk Acoustic Wave ladder filter composed of five resonators were modeled using non-linear modified Butterworth-Van Dyke model. The non-linear characteristics were measured and simulated, and they were compared and found to be fairly identical. The filter's central frequency is 2.12 GHz, the corresponding bandwidth is 61.55 MHz, and the quality factor is 34.55. [ABSTRACT FROM AUTHOR]

This paper presents a ladder-type bulk acoustic wave (BAW) intrinsically switchable filter based on ferroelectric thin-film bulk acoustic resonators (FBARs). The switchable filter can be turned on and off by the application of an external bias voltage due to the electrostrictive effect in thin-film ferroelectrics. In this paper, Barium Strontium Titanate (BST) is used as the ferroelectric material. A systematic design approach for switchable ladder-type ferroelectric filters is provided based on required filter specifications. A switchable filter is implemented in the form of a BST-on-Si composite structure to control the effective electromechanical coupling coefficient of FBARs. As an experimental verification, a 2.5-stage intrinsically switchable BST-on-Si composite FBAR filter is designed, fabricated, and measured. Measurement results for a typical BST-on-Si composite FBAR show a resonator mechanical quality factor (Qm) of 971, as well as a Qm\times f of 2423 GHz. The filter presented here provides a measured insertion loss of 7.8 dB, out-of-band rejection of 26 dB, and fractional bandwidth of 0.33% at 2.5827 GHz when the filter is in the on state at a dc bias of 40 V. In its off state, the filter exhibits an isolation of 31 dB. [ABSTRACT FROM PUBLISHER]

The spatial sensitivity of bulk acoustic mode resonators can influence calibrations when they are implemented as accurate mass sensors of surface-bound particles. A new spatial sensitivity model based on images of the resonator surface is introduced from early principles. The adsorption of particles was studied empirically by repeatedly drying particle laden droplets on the surface of two 3.14 MHz bulk acoustic mode resonators. Theoretical and experimental results were compared to identify three scenarios over the course of consecutive droplet evaporation with varying spatial sensitivity influences. Examining different surface treatments for the resonators revealed the hydrophilic surface to have a higher rate of particle stacking and conglomeration [ABSTRACT FROM AUTHOR]

Implantable medical devices have been facing the severe challenge of wireless communication for a long time. Acoustically actuated magnetoelectric (ME) transducer antennas have attracted lots of attention due to their miniaturization, high radiation efficiency and easy integration. Here, we fully demonstrate the possibility of using only one bulk acoustic wave (BAW) actuated ME transducer antenna (BAW ME antenna) for communication by describing the correspondence between the BAW ME antenna and components of the traditional transmitter in detail. Specifically, we first demonstrate that the signal could be modulated by applying a direct current (DC) magnetic bias and exciting different resonance modes of the BAW ME antenna with frequencies ranging from medium frequency (MF) (1.5 MHz) to medium frequency (UHF) (2 GHz). Then, two methods of adjusting the radiation power of the BAW ME antenna are proposed to realize signal amplification, including increasing the input voltage and using higher order resonance. Finally, a method based on electromagnetic (EM) perturbation is presented to simulate the transmission process of the BAW ME antenna via the finite element analysis (FEA) model. The simulation results match the radiation pattern of magnetic dipoles perfectly, which verifies both the model and our purpose. [ABSTRACT FROM AUTHOR]

State-of-the-art wireless sensor nodes are mostly supplied by batteries. Such systems have the disadvantage that they are not maintenance free because of the limited lifetime of batteries. Instead, wireless sensor nodes or related devices can be remotely powered. To increase the operating range and applicability of these remotely powered devices an electro-magnetic energy harvester is developed in a 0.13 \mum low cost CMOS technology. This paper presents an energy harvesting system that converts RF power to DC power to supply wireless sensor nodes, active transmitters or related systems with a power consumption up to the mW range. This energy harvesting system is used to power a wireless sensor node from the 900 MHz RF field. The wireless sensor node includes an on-chip temperature sensor and a bulk acoustic wave (BAW) based transmitter. The BAW resonator reduces the startup time of the transmitter to about 2 \mus which reduces the amount of energy needed in one transmission cycle. The maximum output power of the transmitter is 5.4 dBm. The chip contains an ultra-low-power control unit and consumes only 190 nW in idle mode. The required input power is -19.7 dBm. [ABSTRACT FROM AUTHOR]

We propose a procedure to characterize the intrinsic nonlinearities of bulk acoustic wave resonators by performing one-port measurements of the second harmonic and second-order intermodulation spurious signals. Closed-form expressions have been derived that relate the nonlinear stiffened elasticity with experimental observables. These formulas are valid in a wide range of frequencies around the resonance and have been verified with nonlinear circuit simulations. The measurement setup and its effects are also discussed in our approach. Measurements of a set of aluminum nitride-based devices from several manufacturers yield consistent model parameters and allow us to obtain a coefficient of the nonlinear stiffened elasticity intrinsic to this piezoelectric material. [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]

Attaching a tire pressure monitoring system (TPMS) on the inner liner of a tire allows sensing of important additional technical parameters, such as vehicle load or tire wearout. The maximum weight of the sensor is limited to 5 grams including package, power supply, and antenna. Robustness is required against extreme levels of acceleration. The node size is limited to about 1 cm3 to avoid high force-gradients due to device-deformation and finally, a long power supply lifetime must be achieved. In this paper a low-power FSK transceiver is presented. Exploiting BAW resonators the use of a bulky and shock-sensitive crystal and a PLL can be avoided. This makes the system more robust and radically reduces the start-up time to 2 μs from few ms as in state-of-the-art crystal oscillator based systems. The current consumption of the transceiver is 6 mA in transmit mode with a transmit output power of 1 dBm and 8 mA in receive mode with a sensitivity of -90 dBm at a data rate of 50 kBitls and a bit error rate of 10-2. The transceiver ASIC and a microcontroller ASIC, a MEMS sensor, and a BAW die are arranged in a 3-D chip stack for best compactness, lowest volume, and highest robustness. The sensor node allows sensing of pressure, acceleration, supply voltage and temperature. [ABSTRACT FROM AUTHOR]

The c -axis zinc oxide (ZnO) multi-layered films and ZnO-based solidly mounted resonators (SMR) based on high-resistivity silicon substrates have been fabricated by using the combination of sputtering and photolithography with the absence of oxygen and heating. Subsequent annealing procedure was performed to improve the quality of ZnO films and devices. The X-ray diffraction (XRD) measurements reveal that all ZnO films are well crystallized and highly textured, the grain size gradually increases from 18.2 to 20.5 nm with the increasing of annealing temperature (T ann). The X-ray photoelectron spectrometer (XPS) results indicate that the high concentration oxygen defects of as-deposited ZnO films can be reduced through increasing T ann. By comparing the measured electrical properties of the devices before and after various T ann annealing, it was found that the annealing treatment can be used to improve the resonance characteristics, the relative change in return loss (S 11) increased from 0 to 0.72 dB and then decreased to 0.07 dB as T ann increases from room temperature to 700 °C. In addition, S 11 relative change can also be enhanced from 0.29 to 0.67 by decreasing the effective working area of the devices from 100 × 160 μm2 to 100 × 50 μm2. [ABSTRACT FROM AUTHOR]

There has been growing interest in exerting radiation forces to trap and cluster randomly distributed cells in body fluid, micro-particles in water, or microorganisms in fluid-like culture media. Acoustic standing waves are extensively utilized as a patterning tool to assemble particles at nodes or anti-nodes but, for frequencies above megahertz, the nodal distances become too small for particle separation. We study a mechanism to propel particles towards one central space by creating a converging wave field without significant reflections. This is achieved by strong decay of the main ultrasound beam by multiple scattering. When two opposing traveling waves are suitably decayed towards their meeting point, a converging wave field is created for particle assembly via radiation forces. This paper describes the theoretical prediction model based on the translation addition theorem and the partial-wave expansion method. The predicted acoustic pressure fields are compared with full numerical simulations for a limited number of particles, and the attenuation coefficient is validated by the existing experimental data. The results demonstrate that the converging wave field is formed, and the acoustic radiation force vectors in a bulk acoustic wave (BAW) device are directed towards the central space for meaningful clustering of micro-particles from their host fluid. [ABSTRACT FROM AUTHOR]

We study the effects of medium rotation on bulk acoustic wave (BAW) propagation. For a theoretical analysis of the BAW propagation characteristics, a motion equation for the plane harmonic waves propagating orthogonal to the rotation axis of the propagation medium was analytically resolved. We found that during medium rotation, the polarization of the waves becomes elliptical with the ratio of the polarization ellipse axes explicitly proportional to the angular velocity of the medium rotation, thereby opening the way for the design of sensitive elements (SE) for perspective angular motion sensors (AMS). Next, an analytical dependence of the SE informative parameter on the Poisson's ratio of the acoustic duct material was obtained. The rotation effect on the dispersion of BAW propagation velocity was studied. Two approaches to the perspective SE design were proposed. An experimental study of a specially designed test assembly and SE model demonstrated high correlation with theoretical predictions and provided an estimate of a potential SE. Therefore, we believe that the study of acoustic wave propagation under nonclassical conditions is a promising direction for prospective solid-state AMS on based on BAW polarization effects design. [ABSTRACT FROM AUTHOR]