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Рассмотрены фильтры на акустически связанных тонкопленочных ОАВ-резонаторах с брэгговским отражателем. Резонатор представляет собой пьезоэлектрический преобразователь на пленках из нитрида алюминия с тонкопленочными алюминиевыми электродами и брэгговский отражатель, состоящий из пяти пар слоев пленок молибдена и алюминия. Представлены результаты моделирования амплитудно-частотных характеристик фильтра на акустически связанных резонаторах с разной площадью электродов. Показано, что с увеличением площади электродов резонатора в 4 раза происходит уменьшение относительной полосы пропускания фильтра (по уровню -3 дБ) в 1,8 раза. Фильтры с центральной частотой 2,77 ГГц и вносимыми потерями -3,1 дБ имеют относительную полосу пропускания в пределах 0,3…0,54 %. Максимальное гарантированное затухание в полосе задерживания при отстройке на 5 % составляет -34,7 дБ.

A general approach, which can efficiently and automatically derive dispersion relations for infinite layered structures with any number of piezoelectric and elastic layers, is proposed in this paper. Based on the Stroh formalism and the dual variable and position method, the general relationship between top and bottom variables of a single layer is obtained first. Considering the different layups possibly appearing in multi-structures, three base cases are presented in detail. By combining these base cases repeatedly from the bottom of the plates to the top, we can easily write programming codes to derive dispersion relations for any general multilayered structure automatically. To verify this approach, dispersion curves and mode shapes for the film bulk acoustic resonator and the stacked crystal filter are presented in this paper. The results show good conformity with reported works and simultaneously prove the ability of our approach for complex and generally anisotropic multilayered structure. Above all, this general approach is efficient and superior to get the dispersion relations, which is convenient for further study of wave propagation characteristics in general multilayered structures.

The accurate detection of weak current signal plays an important role in academic, industrial, daily life, and other fields. However, the weak current signals of nano-ampere levels are easily affected by sensor noise, electronic device noise, and others, which makes the precise detection of weak current signal become critical issues. Based on these challenges, to improve the detection ability of weak current signal at a specific frequency band, this paper proposes a current-voltage conversion circuit based on resonant amplifiers and a crystal filter. The resonant amplifiers convert and amplify the weak current signal, firstly. Moreover, a crystal filter is used to further compress and filter the noise and harmonics in a weak current signal. Practical test results show that this proposed weak current conversion circuit has good performance that the maximum spurious-free dynamic range improvement can be 73.9dB.

The miniature high-frequency monolithic crystal filter is developed according to the requirement of model. The main electrical performance of the monolithic crystal filter is better than that of technical specifications, and the parameters of passband bandwidth, insert loss, passband ripple, shape factor, parasitic suppression, stopband attenuation meet the requirements of users.

12. 76MHz discrete crystal filter adopts AT cut quartz resonator and differential bridge circuit design. The bandwith of 3dB passband is up to 60kHz at the operting temperature range of -20°c ∼ 60°C. The filter features advanced circuit design, reasonable component application, voltage standing wave ratio less than 2.0. The components are mounted and sealed with tin, and the whole structure is shielded and isolated. The successful development of this product provides a frequency selection device for electronic systems such as tactical mission and radar systems which require extremely high signal reception and transmission under severe conditions. The electrical performance test data and result analysis of the 12. 76MHz discrete crystal filter are given.

Quartz crystal units (CUs) are the most popular oscillating components in high-quality crystal filters and oscillators, due to their electrical and mechanical characteristics. This paper considers design and realization of high quality 76.8375 MHz crystal filter based on third overtone quartz crystal units. In addition to the basic parameters, this filter also meets the special operational conditions of the environment (clime and mechanical conditions). Filter design and requested specifications are further explained as well as the resulting transfer function of the 76.8375 MHz filter.

Filters based on two acoustically coupled thin-film BAW resonators with a Bragg reflector are considered. The every resonator consists of the piezoelectric transducer based on aluminum nitride layer with thin-film aluminum electrodes. The Bragg reflector is total for the filter and is made of five pairs of molybdenum and aluminum layers. The results of modeling the amplitude-frequency characteristics of the stacked crystal filter based on BAW resonators having different electrode areas are presented. It is shown that with increasing the area of the resonator electrodes by 4 times the relative bandwidth (at −3 dB level) of the filter decreases by 1.8 times. Filters with a center frequency of 2.77 GHz and an insertion loss of −3.1 dB have a relative bandwidth in the range of 0.3…0.54 %. The maximum guaranteed stopband attenuation at 5 % offset is −34.7 dB.

This filter uses liquid crystal (LC) as the electro-optic material. It can realize frequency shift by changing the dielectric anisotropy, when the bias voltage is added. It is mainly used in microwave frequencies. According to the simulation results, it achieves the center frequency with 770 MHz offset. It has many advantages compared to conventional filter, such as low weight, ability of continuously tunable, miniaturization, low processing costs, low tuning voltage, convenient manufacture, etc. Therefore, it has shown great potential for modern engineering application.

In this paper, a variation-aware and reliable design of a fully integrated radio frequency (RF) bandpass filter realized using a voltage differencing transconductance amplifier is presented. The filter is characterized by its high frequency operation, low power consumption, high quality factor, and it is insensitive to process, voltage, and temperature variations. Sensitivity analysis has been performed to analyze the circuit performance in the presence of parasitics. The inductor-less approach finds its application in integrated building blocks of RF front ends, thus eliminating the requirement of off-chip filters in transceivers. Centered at 2.511 GHz and operating within the 36.21 MHz 3-dB bandwidth, the filter draws 0.168 mA from a ±1 V power supply, attains a voltage gain of 72.6 dB, a quality factor of 69.34 and noise figure of ~29.6 dB. In addition, it has a dynamic range of 125.84 dB-Hz and a 1-dB compression of −1.5 dBm which translates into a figure of merit as high as 94 dB.

This paper presents a low loss electrically tunable bandpass filter based on liquid crystal. By utilizing structure of transmission line and direct-connected feeding lines without coupling gaps which eliminate mismatch and radiation losses, then the proposed filter gets a low insertion loss. And the tunability of the filter is realized by utilizing electrically controlled liquid crystal (LC) material as the substrate. In order to verify the design concept, a liquid crystal tunable prototype filter is designed, fabricated and measured. Measured results agree well with the simulated results. With no bias voltage applied, the filter operates at center frequency of 11.5 GHz with fractional bandwidth of 11.3%. And with voltage tuning from 0 V to 10 V, the filter gets a tuning range of 500 MHz and the insertion losses are 2–3.1 dB, respectively.

A nanoscale phononic crystal filter (reflector) is designed for a kinetic inductance detector where the reflection band is matched to the quasiparticle recombination phonons with the aim to increase quasiparticle lifetime in the superconducting resonator. The inductor is enclosed by a 1 um wide phononic crystal membrane section with two simple hole patterns that each contain a partial spectral gap for various high frequency phonon modes. The phononic crystal is narrow enough for low frequency thermal phonons to propagate unimpeded. With 3D phonon scattering simulations over a 40 dB attenuation in transmitted power is found for the crystal, which was previously estimated to give a lifetime enhancement of nearly two orders of magnitude., 7 pages, 3 figures, 18th International Workshop on Low Temperature Detectors (Milan, 2019)

An intrinsically switchable ferroelectric barium strontium titanate (BST) stacked crystal filter (SCF) is presented for the first time. A single pole BST SCF is designed for a second overtone (mode 2) operating at 3.6 GHz. The fabricated device provides a high out-of-band rejection and off state isolation of more than 25 dB, which is a >10 dB improvement over a single stage BST ladder-type structure with similar specifications. The measured insertion loss and 3-dB fractional bandwidth (FBW) are shown to be 3 dB and 4.3%, respectively. These metrics are obtained for a single pole SCF, which occupies a footprint of less than 400 (μm)2, significantly more compact than traditional acoustic filters.

In order to improve frequency selectivity of microwave devices and raise the frequency spectrum efficiency effectively, a new kind of microwave continuously tunable Split Ring Resonator (SRR) band-pass filter, using the field-induced nematic liquid crystal, is presented in this paper. Based on the fundamental theory of the electro-optic effect of liquid crystal, applying the bias voltage on liquid crystal can change its permittivity to mainly realize passband frequency shift at microwave band. The frequency characteristics of the filter are analysed. The proposed parameter extraction on the base of the frequency characteristics can easily analyze distributing parameter circuit about this liquid crystal filter. The simulation results shows that this liquid crystal tuning filter achieves 750 MHz offset obviously. Compared with the other tuning techniques, the liquid crystal tuning technology has many advantages, such as continuously tuning, miniaturization, low tuning voltage, etc. Thus, it shows great potentials for modern communication applications.

We report our work in developing microelectromechanical systems (MEMS)-based Ultra High Frequency (UHF) AT-cut quartz monolithic crystal filters operating between 350 and 400 MHz for integration with Si electronics for highly compact Radio Frequency (RF) front-end electronics. Our narrow bandwidth (0.2%) high $Q$ filters have measured insertion losses of −2 dB with temperature stability of roughly 50 ppm over a temperature range of 10°– 80°C. Wafer-level optical metrology and ion milling techniques have been developed to provide enhanced accuracy of the filter center frequency and resonator parameters for optimized performance and improved yields. [2015-0163]

Photonic crystal based ring resonators are promising structures used for designing optical filters suitable for optical communication networks. In this work we use an H-shaped resonant ring for designing an optical filter. The proposed filter consists of two upper and lower waveguides coupled through an H-shaped resonator which is designed for coupling of an identical wavelength from upper waveguide to the lower one. We use numerical methods such as plane wave expansion and finite difference time domain for performing our simulations and studying the optical properties of the proposed structure. The transmission efficiency and quality factor of our filter is about 100% and 221 relatively.

Ideal bandpass filters must have sharp roll-off and high transmission over a target pass band simultaneoulsy, but it is still difficult to make such filters of a reasnoable size. To achieve such performance, we propose a novel finite phononic crystal filter made of impedance-mirrored elements each of which constists of two layers having different impedances. For broad bandpass filtering, one of the two layers is selected to be one eighth wavelength long at the center frequency of the passband and the other layer, one quarter wavelength long with a matched impedance. For narrow bandpass filtering, the broad bandpass filter is slightly modified in such a way that the concept of the impedance-mirroring is applied globally over the finite periodic structure filter, not within each unit cell. To check the performance of the proposed filters, experiments using torsional elastic waves in a rod were conducted.

Monolithic crystal filter (MCF) on AT-cut quartz for application in viscosity sensor was developed. After proper matching, at a frequency of $\sim 3.6$ MHz, insertion loss in air of $\sim 1.6$ dB was obtained. The linear coefficient of frequency of about −5 ppm/°C and changes of the insertion loss of $\sim 0.5$ dB, in the temperature range of 10°–80°, were obtained. To eliminate errors caused by the longitudinal acoustic wave generation, MCF should be immersed in a measured liquid or proper amount of liquid should be inserted into the sensing window. Using water and glycerin solutions, insertion loss changes against dynamic viscosity of the MCF were measured. In a viscosity range from about 1 to 1000 $\textrm {mPa}\cdot \textrm {s}$ , an insertion loss change of $\sim 24$ dB was obtained.

We studied thickness-shear and thickness-twist vibrations of a monolithic, two-pole crystal filter made from a plate of AT-cut quartz. The scalar differential equations derived by Tiersten and Smythe for electroded and unelectroded quartz plates were employed which are valid for both the fundamental and the overtone modes. Exact solutions for the free vibration resonant frequencies and modes were obtained from the equations. For a structurally symmetric filter, the modes can be separated into symmetric and antisymmetric ones. Trapped modes with vibrations mainly under the electrodes were found. The effect of the distance between the two pairs of electrodes was examined.

The voltage divider phase shift filter (VDPSF) has been used in the past to construct inductorless narrowband filters with moderately high Q values, for example, Q = 50. This work reports a new configuration of this filter that can achieve extremely high Q values over a range of frequencies from very low to very high values. A typical value is Q = 2500, but can be even higher. These high values of Q can be obtained at very low frequencies, solving a long-standing problem for LC tank circuits. The new configuration consists of one voltage divider phase shift filter nested within a second such filter. A simulation is done to verify the accuracy of the theory and demonstrate the stability of Q with respect to circuit element value changes. One significant application of such a filter is in the creation of a tunable oscillator with a very high degree of spectral purity.

Massive MIMO technology and mm-wave band radio communication are effective solution of a high data rate for 5G. This paper presents a novel 28GHz wideband filter for those antenna units. To realize a wide fractional bandwidth of 10%, a new terminal configuration of “Y-shaped” structure is proposed. A TEM-TE mode transition function using the new structure was analyzed, and the shape was optimized. Applying the new terminal structure to an 8-pole with 2 trap quartz waveguide filter, high performances such as very low loss of 1.2 dB, wide relative passband of 10.4% and high attenuation of more than 50dB were obtained with a small size and SMD structure.

This paper focused on AT-cut disc-typed quartz crystal resonator, which is one of commonly used sensitive components of quartz resonator sensor. The harmonic analysis and modal analysis of the typical AT-cut quartz crystals were performed by using the finite element method. The result shows that the harmonic frequency is close to the theoretical value. Based on the analysis of harmonic frequency, the paper has obtained the clear thickness-shear mode vibration and amplitude-frequency curve of quartz crystals. It provides a foundation for the research of quartz resonator sensor.

This article proposes a novel method for the temperature-compensated inductance-to-frequency converter with a single quartz crystal oscillating in the switching oscillating circuit to achieve better temperature stability of the converter. The novelty of this method lies in the switching-mode converter, the use of additionally connected impedances in parallel to the shunt capacitances of the quartz crystal, and two inductances in series to the quartz crystal. This brings a considerable reduction of the temperature influence of AT-cut crystal frequency change in the temperature range between 10 and 40 °C. The oscillator switching method and the switching impedances connected to the quartz crystal do not only compensate for the crystal’s natural temperature characteristics but also any other influences on the crystal such as ageing as well as from other oscillating circuit elements. In addition, the method also improves frequency sensitivity in inductance measurements. The experimental results show that through high temperature compensation improvement of the quartz crystal characteristics, this switching method theoretically enables a 2 pH resolution. It converts inductance to frequency in the range of 85–100 µH to 2–560 kHz.

Photonic crystal ring resonators are promising candidates for realizing all optical filters with acceptable transmission efficiency and quality factor values. In this paper, by putting a12-fold quasi crystal at the middle of on 7 × 7 square cavity we created a ring resonator structure and designed a T-shaped channel drop filter. The drop wavelength of our filter is at 1551 nm, with transmission efficiency and quality factor equal to 90% and 387. Our structure is composed of dielectric rods immersed in air. Because in this kind of structures the dominant band gap is in TM mode, all of our simulations have been done in TM mode. The total footprint of our filter is 242.4 μm2, which makes it suitable for all optical integrated circuits.

Designs of optical resonators comprising a half-wavelength dielectric layer bounded from both ends by quarter-wavelength layers with permittivity higher or lower than that of the half-wavelength layer are investigated. Electrodynamic analysis demonstrates a significant increase in the Q-factor of the multilayered resonator in comparison with the conventional single-layer half-wavelength resonator. Principles of designing highly selective passband filters based on photonic crystal structures are considered.

A new type temperature-insensitive quartz filter is presented in this paper, which is composed of three polarizers, a quartz birefringent crystal and a quartz rotation crystal. Based on the principle that the fluctuations of the quartz birefringence and specific rotation have an opposite trend with the temperature change, the temperature effect on output center wavelength of this new type quartz filter is investigated in detail theoretically and experimentally. The theoretical and experimental results show that this new type quartz filter is indeed insensitive to temperature change. It will have a certain application in the stability output of optical filter when temperature change as we believe.

In this paper the temperature effect on the transmission spectrum of the quartz optical rotation filter is investigated theoretically and experimentally in detail, which shows that the output center wavelength of filter will shift towards the long wavelength with the temperature increasing and the output center wave-length of filter will shift towards the short wavelength with the temperature decreasing. The simulation and the experiment results are the same basically. According to this conclusion, a new type quartz optical rotation filter that is insensitive to the changing temperature is proposed.

A fifth order X-band waveguide bandpass filter, based on spherical resonators, has been designed, and fabricated by 3-D printing. In comparison with rectangular waveguide, spherical resonators have a higher unloaded quality factor, but at the same time suffer from closer higher order modes. In this letter, a special topology has been proposed to relieve the impact of the first three higher order modes in the resonator and ultimately to achieve a good out-of-band rejection. Stereolithography based 3-D printing is used to build the filter structure from polymer and a 25 $\mu{\rm m}$ thick copper layer is deposited to the filter. The measurement result of the filter has an excellent agreement with the simulations. The filter is also considerably lighter than a similar metal filter.

We have designed a tunable two dimensional (2D) channel drop filter (CDF) based on photonic crystal ring resonators (PCRR). Dropping efficiency and Q factor of single improved ring are 100% and 842, respectively. In this filter the quality factor is significantly improved with respect to other published reports. We investigate parameters which have an effect on resonant wavelength in this CDF, such as dielectric constant of inner, coupling, adjacent and whole rods of the structure and radius of inner rods. The transmission spectrum for our proposed configuration has been investigated using the 2D finite difference time domain (FDTD) method. The area of the proposed structure is about 117 μm 2 .

A tunable filter was designed, which using the liquid crystal as defect films based on the one-dimensional ternary photonic crystal. The spectrum transmission was obtained by using the transfer matrix method, analyze the properties of the band gap of the 1D ternary photonic crystal and main factors influencing the tunable filter. The results show that the filter has different job windows by changing the thickness increment of the adjacent medium behind the liquid crystal, and the tuning range of which has 30nm and above .

The effect of temperature and angle of incidence on the transmission spectra of a one dimensional photonic crystal for TE and TM polarizations has been studied. For a range of angle of incidence from 0° to 60°, the proposed structure works as an omni-directional reflector. For other angles of incidence more than 60°, the structure works as a selective TM-polarization filter i.e. a filter which completely blocks TE-polarized waves but allows certain frequencies of TM-polarized waves. At an angle of incidence of 89°, the structure works as a multi channel optical filter without introducing any defect in the geometry. Also, this multi-channel filter can work as a tunable filter by varying the temperature of the structure and the number of layers in the geometry. Only for two bi-layers the proposed structure works as a single channel filter. Therefore, such types of structure are easier to fabricate and may be cost effective as compared to defect one-dimensional photonic crystals.

Crystallization is a commonly used method for the purification and formulation of proteins. In order to harmonize crystallization with the mechanical separation process, it is necessary to estimate early the separation conditions of protein crystals. To fulfill this requirement, the feed material for filtration is minimized by reducing the filter area. The filtration behavior of lysozyme crystals in pressure filters with two different filter areas was compared. Crystal slurries with different mean crystal sizes and shapes were produced and the influence of the size and shape on the scalability of filtration data was examined. It was found that for different aggregated crystal structures and isometric crystals, the larger the compressibility of the cake was, the larger were the deviations for the two considered filter areas. For needle-shaped crystals, the compressibility was not subject to deviations, but the absolute filter cake resistance was. Furthermore, the deviations of the cake resistances increased with higher pressures for all product systems. It was indicated that upscaling from the small filter area is possible for low compressible product systems and at low pressures. With high compressible products and for needle-like crystals, the filtration time is underestimated with the small filter area.

A new-style tunable photonic crystal filter was proposed, its structure is the liquid crystal defect films are introduced to the one-dimensional photonic crystal periodically composed by three different refractive index mediums. The spectrum transmission was obtained by using the transfer matrix method and liquid crystal Jones' matrix, we synthetically analyze the properties of the complex period photonic crystal infiltrated with nematic liquid crystal and the influence of many factors such as liquid crystal thickness, photonic crystal periodicity and adjacent medium thickness increment. The filter has different job windows in 1550 nm、1330nm etc, by changing the thickness increment of the adjacent medium behind the liquid crystal, and the tuning range of which has 30nm and above .

The target of analog and RF filtering is to modify the magnitude and phase of signal frequency components. Many analog or radio frequency (RF) circuits perform filtering on the signals passing through them.

This paper presents a fourth-order synthetic Q-enhanced LC band-pass filter (BPF) in 0.13 µm SiGe BiCMOS, where 4th-order BPF response has been synthesized by subtracting two 2nd-order BPF responses. Operating frequency of the filter is tunable from 4–8 GHz. Using a switched-varactor control for a high linearity, the filter achieves 150–166 dB · Hz normalized dynamic range (DR) with a tunable fractional bandwidth range of 2–25% at the center frequency of 6 GHz. The ultimate out-of-band rejection of the filter is > 65 dB and > 52 dB on the lower and upper side of the center frequency, respectively. The filter consumes 112–125 mW of DC power dissipation. The core chip size is 0.53×0.7 mm2.

In the paper a planar circular model (20-by-20 µm in size) of a band-pass multiplexing filter, based on 2D photonic crystal with original “dewdrop-petal” inner structure has been considered. The frequency selectivity of this filter is due to its geometry, built on the base of nature processing physical system - a flower with dewdrops on its petals. The filter has been PCsimulated on TE electromagnetic waves in a band of wavelengths between 2 and 12 µm.

Multispectral tunable filters with high performance are desirable components in various biomedical and industrial applications. In this Letter, we present a new narrowband multispectral tunable filter with high throughput over a wide dynamic range. It is composed from a wideband large dynamic range liquid crystal tunable filter combined with a multiple narrowbands spectral filter made of two stacks of photonic crystals and cavity layer in between. The filter tunes between nine spectral bands covering the range 450-1000 nm with bandwidth10 nm and throughput80%.

The application of active elements such as gyrator and negative capacitance simulator in conjunction with piezoelectric resonators allows to imitate simple LC circuits employed in bandpass, low-pass and high-pass filter design. In contrast to the circuits composed of distributed elements, active circuits with resonators provide minimal sensitivity to component variations and less parameter offsets during production. They also have smaller dimensions and can be integrated with digital signal processing on a single chip including the possibility electronic adjustment. The replacement principle of LC circuit prototypes by the active analogs is described in details. The active low-pass filter was designed and analyzed using the presented approach to review the special considerations about resonators application.

International audience; Bulk acoustic wave (BAW) quartz crystal resonators working at liquid helium temperature are an exciting topic of interest. Indeed, high-quality devices can exhibit quality factors of a few hundreds of millions, from tens of megahertz to hundreds of megahertz, and can reach a few billions for the best ones. As a consequence they are good candidates to various applications ranging from frequency references to fundamental physics. A brief review is first proposed regarding Q-factor properties of BAW SC-cut resonators within the temperature range 3K - 12K. The A, B and C mode behaviors are also examined in terms of frequency versus temperature, as well as the frequency dependence with the excitation power. Finally measurements on Nyquist noise are presented.

This paper presents the design, manufacturing and testing of a new type of compact and low loss Ka-band filter in multilayer micromachined technology. It consists of a 4th order pseudo-elliptic filter realized by stacking six silicon layers for a reduced footprint. The filter is based on λ/2 TEM Si membrane resonators placed inside shielding cavities and short-circuited at both anchored ends. With respect to conventional cavities based on TE101 resonant mode, the footprint of the proposed resonators is reduced by more than 50% at the expenses of a reduced Q factor degradation (