Resonator Filters Research Articles

Design and Fabrication of Temperature-Compensated Film Bulk Acoustic Resonator Filter Based on the Stress Compensation Effect

To ensure that the performance of filters matches the continuous development in communication frequency bands, the influence of temperature on filter performance must be considered during the fabrication of filters. In this study, a cavity-type temperature-compensated film bulk acoustic resonator (TC-FBAR) device was prepared with an SiO2 temperature filter between the bottom electrode and the piezoelectric layer. A one-dimensional Mason model of the TC-FBAR was established. An advanced design system, a high-frequency structure simulator, and COMSOL software were used to optimize the design of the TC-FBAR. After the optimization, the out-of-band rejection was improved by 10 dB. To address the compensation effect of the tensile and compressive stresses, a multilayer film was implemented for low-stress control and a reduction in stress to |P| ≤ 150 MPa, thereby improving the orientation of the piezoelectric film. Moreover, the influence of the thickness of the SiO2 temperature-compensated layers on the temperature-compensated characteristics was studied. When the SiO2 thickness was 50 nm, the temperature coefficient of frequency (TCF) was ±1 ppm/°C. The center frequency and 3 dB bandwidth of TC-FBAR were 2.492 GHz and 15.02 MHz, respectively, and the center insertion loss was −3.1 dB. Moreover, the out-of-band rejection was greater than 40 dBc, and TCF was 0.8 ppm/°C.

Fast FBG Interrogator on Chip Based on Silicon on Insulator Ring Resonator Add/Drop Filters

A fast FBG sensor interrogator on chip based on SOI ring resonator (RR) filters is presented. The measurement of the Bragg wavelength shift is based on the detection of multiple signals at the output ports of the RR filter, providing fast dynamic strain measurement capabilities, fundamentally limited by the photodetector bandwidth and signal processing. The ring resonator resonance wavelength is tuned and fixed by an integrated heater and the ring acts as a passband filter for the reflected FBG spectrum. After a theoretical analysis of the interrogation method, which allows the optimization of the RR characteristics depending on the specific application and requirements, we present experimental results on a single RR based interrogation scheme applying high frequency dynamic strain up to 40 kHz. We also theoretically evaluate the performance of multi-ring resonators. The proposed scheme provides low cost, high scalability to mass-volume market applications as well as an extremely fast interrogation method.

Substrate Integrated Waveguide Quasi-Elliptic Filter with Arbitrary Termination Impedances

This paper presents a quasi-elliptic filter (QEF) with arbitrary termination impedances (ATI). The proposed QEF is designed by adding cross-coupling between the first and last resonators of an ATI bandpass filter (BPF) with the Chebyshev response. The proposed QEFs with ATI can be designed in even-order resonators and the location of the pair transmission zeros (TZs) is controllable. To prove the validity of the proposed design, the fourth-order QEFs with ATI were implemented on a single-layer substrate-integrated waveguide (SIW) cavity at a center frequency (<i>f</i><sub>0</sub>) of 10 GHz with the pair TZs at 10 ± 1.4 GHz. These SIW QEFs with ATI improve frequency selectivity and effectively suppress the out-of-band signal with high power handling. The measured maximum insertion loss (|<i>S</i><sub>21</sub>|) and minimum return loss (|<i>S</i><sub>11</sub>|) of the SIW QEF with unequal real-to-real ATI are 0.93 dB and 17.4 dB, respectively, in the passband. Similarly, the maximum |<i>S</i><sub>21</sub>| and minimum |S<i>S</i><sub>11</sub>| of the SIW QEF with complex-to-real ATI are 1.2 dB and 18 dB, respectively.yer substrate-integrated waveguide (SIW) cavity at a center frequency (

An Improved Permanent Magnet Synchronous Motor Rotor Position Observer Design Based on Error Harmonic Elimination

An improved rotor position observer based on sliding mode control was proposed to eliminate estimation error and harmonic ripples for PMSM sensorless control. A multi-proportional resonant filter was designed instead of a low-pass filter to filter out the specific harmonics of back EMF. The improved filter can solve the phase delay problem caused by a low-pass filter, eliminate the rotor angle compensator, simplify the system structure, and effectively suppress the system chattering. Then, a fractional normalized phase-locked loop was adopted to calculate the speed and rotor position, further eliminating the influence of noise. Compared with the traditional sliding mode control and the improved sliding mode control, the improved sliding mode observer can effectively suppress the back EMF chattering and reduce the speed estimation error. The correctness and effectiveness of the proposed improved sliding mode observer were verified through the simulation model and experimental platform of PMSM sensorless control.

Accurate Circuit Parameter Determination of a Resonant Power Frequency Converter for High-Voltage and Partial Discharge Tests

For high-voltage (HV) and partial discharge (PD) tests on high-voltage equipment, a resonant power frequency converter has recently been developed. A single-phase power frequency converter with a resonant tuning and filter circuit and an HV testing transformer comprise the developed system. A difficulty in the tuning and filter circuit design is the unknown testing system circuit parameters, including unknown parasitic inductance, capacitance, and internal resistance. In this paper, a system with a voltage rating of 75 kVrms, apparent power of 40 kVA, and an operating frequency from 50 Hz to 200 Hz is considered for determination of the equivalent circuit parameters. From the determined circuit parameters, the appropriate resonant tuning and filter circuit was designed effectively. The transfer functions of the input and output testing voltages, along with the transfer impedance of the input voltage and signal voltage of the PD measuring port, were analyzed. The system design was verified by experiments with a voltage transformer. The gain of the transfer impedance was about 15 and 4 at the testing frequencies of 50 Hz and 200 Hz, respectively. With the proper design, it is possible to generate an output voltage waveform that is almost entirely sinusoidal and has a background noise level of under 1 pC. According to the experimental results, the system design of the resonant converter and the method for determining the equivalent circuit are very helpful for the HV and PD tests of voltage transformers in actual practice.

A wideband omnidirectional planar filtenna for 5 GHz WLAN application

This paper presents a wideband planar filtenna based on the filter synthesis technique. The proposed filtenna consists of a third order hairpin line resonator filter coupled with an elliptical antenna. One arm of the last resonator of hairpin line resonator along with the extended feed arm of an antenna constitute an admittance inverter, which provides better integration between filter and antenna. The measured results show that the proposed filtenna exhibits a filtering response with impedance bandwidth of 26.5% (4.19–5.47 GHz), flat passband gain, good selectivity at band edges and omnidirectional radiation pattern well suited for WLAN application.

A Direct Discrete-Time Output Feedback-based LS-RMRAC for Grid-tied Current Control Loop of a Static 3-Wire Converter under Unbalanced Grid Voltage Conditions

Nowadays, renewable energy generation is a worldwide tendency. These clean sources are generally tied to the grid by voltage-fed static converters. In this work, a direct discrete-time Output Feedback-based LS (Least Squares)-RMRAC (Robust Model Reference Adaptive Control) is proposed for grid-side current loop control of a static 3-wire converter connected to the grid through LCL filter. The proposed control method mitigates the LCL filter resonance,rejects grid disturbances without needing Resonant Controllers implementation, and deals properly with grid uncertainties and parametric variations, being suitable for grids with unbalanced voltage conditions. Simulation results of proposed controller are presented. Keywords: Robust Adaptive Control. Grid-tied converter. LCL filter.

Single-Phase Grid-Interactive Inverter With Resonance Suppression Based on Adaptive Predictive Control in Weak Grid Condition

This article presents an effective resonance suppression control for grid-interactive inverters with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> filter in weak grid conditions. The resonance suppression mechanism is based on an adaptive model predictive control (AMPC). The large parasitic impedance and low short-circuit ratio (SCR) of weak grid challenges the operation of grid-interactive inverters. Specifically, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> filter resonance may get excited, resulting in collapse of the inverter operation. The proposed AMPC scheme autonomously alter the controller objectives for suppressing the resonance. The proposed control scheme alters the feedback currents based on the grid-condition. During the stiff grid conditions, grid current serves as feedback to the controller. While in the weak grid conditions, the inverter current is selected as feedback signal. The toggling action between these two feedback currents is determined by comparing moving RMS of grid current with desired current as constraint in the proposed AMPC cost function. The performance of proposed controller is verified experimentally. The results demonstrate that the proposed controller features robust performance under various grid conditions, model parameter mismatch, grid disturbances, seamless transition between controller modes of operation and feedback alteration to attain resonance suppression, eliminates required tuning efforts in comparison to classical multi-nested loop control schemes, and provides high power quality according to IEEE standard 1547.

Studies on of phase error oscillations in a class of third-order optical phase locked loop and its effect on a slave optical phase locked loop

Dynamics of a third-order optical phase locked loop (OPLL) with a resonant type loop filter (LF) has been studied analytically and numerically. The range of stable synchronous operating zone of such OPLL has been estimated analytically in system and signal parameters and obtained predictions are in good agreement with numerical results. Beyond the stable region, it is found that chaotic oscillation of phase error occurs through a sequence of period doubling bifurcation. In addition to this, tracking of such periodic as well as chaotic dynamics of third-order OPLL by another OPLL in master-slave configuration has also been explored here. The tracking is possible by slave OPLL within a very short range of effective frequency offset by keeping other design parameters within the stable mode of operation. The synchronization of the master and slave OPLLs has been studied in generalized sense by considering auxiliary system. The study is very important and helpful for optical signal processing and also in chaos-based secure communication.

Dual mode dielectric resonator filter with a new source coupling slot approach

In this study, a Ka-band dual-mode dielectric resonator filter is studied. As a new approach, to mount the dielectric resonator on the input coupling slot, a mechanical protrusion is designed. By use of this structure, controlled source coupling and excitation via waveguide can be allowed. Compared with coaxial cable excitation, waveguide excitation allows high power handling capacity and less insertion loss.

High-Quality Film Bulk Acoustic Resonators Fabricated on AlN Films Grown by a New Two-Step Method

The quality enhancement of sputtering AlN has hampered a bottleneck that limits the further development and deployment of film bulk acoustic resonator (FBAR) filters. To address this bottleneck, a new two-step growth process integrating metal–organic chemical vapor deposition (MOCVD) and physical vapor deposition (PVD) technologies was carefully constructed to grow AlN films on Si substrates. It was found that both the crystallinity and the surface roughness were increased by more than double that of the one-step produced PVD AlN because of the MOCVD AlN buffer layer with smaller dislocations and grain boundaries. Afterward, using our 4-inch MEMS wafer process, high-quality AlN-based FBARs wafers were obtained accordingly with small full-width at half-maximums for two-step grown AlN(0002) X-ray rocking curves of 0.68°, showing that the Q-factor of FBARs with two-step grown AlN precedes FBARs with one-step grown PVD AlN by 57.6%.

A Dispersive Quadruplet Structure for Monoblock Dielectric Resonator Filters

In this article, a dispersive quadruplet structure that can flexibly control the rejection response of a high- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> monoblock dielectric resonator (MDR) filter using a shared cavity is introduced. Being simple in structure, traditional partitioning walls for positive couplings are replaced by metalized through holes. The dispersion effect of the blind hole for negative coupling can be effectively compensated by parasitic cross couplings by appropriately managing the through holes, leading to a shared rectangular cavity for the resonators. With the aggregated effort of the blind hole and through holes, the rejection response can be well controlled to a certain extent. The closed-form mathematic transformation from the dispersion-less to dispersive coupling matrices of the quadruplet is also given for explaining the working principle of the dispersive quadruplet and providing a design guideline. Two design examples are presented: a quadruplet MDR filter with two symmetric transmission zeros (TZs); and an eight-pole MDR filter consisting of a proposed quadruplet and a box unit, showing superior performance of the MDR quadruplet structure in realizing a wide range of rejection responses and validating the theory for practical applications. The experimental result demonstrates that the MDR quadruplet is particularly useful when rejection specifications near the passband are stringent.

A Wide Stopband Dual-Band Bandpass Filter Based on Asymmetrical Parallel-Coupled Transmission Line Resonator

A self-coupled resonator consisting of asymmetrical parallel-coupled microstrip transmission lines is proposed to design wide stopband dual-band bandpass filters. Due to the even-to-odd-mode analysis limitation to asymmetrical structure, a multiport analysis method is developed and applied to analyze the proposed self-coupled resonator and dual-band filter. According to the analysis, the proposed self-coupled resonator features a small frequency ratio of the second to the first resonances and controllable spurious responses, and its transmission zeros (TZs) are placed close to the position out-of-band spurs in order to achieve wide stopband. Moreover, a feed line consisting of tapped line loaded coupled line is investigated, resulting in flexible adjustment of the second passband external quality factor ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${ \boldsymbol Q}_{ \boldsymbol e}$ </tex-math></inline-formula> ) with a minor influence on the first passband <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${ \boldsymbol Q}_{ \boldsymbol e}$ </tex-math></inline-formula> . A dual-band BPF prototype with a frequency ratio of 1.59 is proposed and validated. It is operated at 2.34 and 3.72 GHz with the insertion loss of 1.05 and 1.86 dB, respectively. A return loss better than 20 dB is achieved at both passbands. The out-of-band rejection is better than 30 dB within the frequency range from 4.19 to 11.24 GHz, and the harmonic suppression is 39.97 dB at 14.88 GHz and 61.41 dB at 18.6 GHz. The measured results verify the analytical method presented in this article well.

An MOR Algorithm Based on the Immittance Zero and Pole Eigenvectors for Fast FEM Simulations of Two-Port Microwave Structures

The aim of this article is to present a novel model-order reduction (MOR) algorithm for fast finite-element frequency-domain simulations of microwave two-port structures. The projection basis used to construct the reduced-order model (ROM) comprises two sets: singular vectors and regular vectors. The first set is composed of the eigenvectors associated with the poles of the finite-element method (FEM) state-space system, while the second one is made up from the eigenvectors corresponding to the zeros of the diagonal elements of the matrix-valued immittance transfer function. Importantly, just one LU factorization of the FEM system is required to construct the projection basis during the reduction process, due to the application of a new formulation based on the Schur complement. The sets of eigenvectors that are used in the basis are independent of one another, which makes the new technique better suited for parallel computing compared with previously developed methods, which are sequential in nature. The reliability and accuracy of the proposed scheme are compared with that of the standard MOR technique, namely, the reduced-basis method (RBM), and verified through the analysis of three microwave structures: an eighth-order dual-mode waveguide filter, a dielectric resonator filter, and a folded waveguide filter.

A novel cross‐coupled filter with triangular resonators

In this article, a novel isosceles right triangle resonators filter is presented based on cross-coupling technology. The whole filter is a square structure and it consists of four isosceles right triangle resonators. By introducing negative cross-coupling between two resonators, a fourth-order cross-coupling dielectric waveguide filter with two out-of-band transmission zeros (TZs) is implemented. By changing the sign of the coupling coefficient, the TZ can be changed around the passband. Positive coupling is achieved through a coupling partition and shallow coupling blind holes, and negative coupling is achieved through symmetrical upper and lower blind holes. The new resonator structure is introduced and the design, simulation, and physical measurement of the filter are discussed. The results show that the center frequency of the filter is 3.5 GHz and the relative bandwidth is 5.7%. The passband return loss is more than 14 dB, the insertion loss is less than 0.1 dB.

Switchable dual-functional guided-mode resonant filters based on VO2 phase transition

Here we propose a hybrid dielectric waveguide grating with an ultrathin vanadium dioxide (VO2) thin film for achieving switchable dual-functional GMR filters. We show that, when the VO2 thin film undergoes the insulator-to-metal phase transition, the hybrid dielectric waveguide gratings enable the switch between the reflection and transmission filters. This work expands the research topic of GMR and provides valuable strategy for the design of novel reconfigurable devices for photonics.

A computer‐aided design tool for RF filters design automation

SummaryIn this paper, we propose a computer‐aided design (CAD) tool in the electronic design automation (EDA) domain. This tool is dedicated for the design and simulation of Radiofrequency (RF) filters that are integrated into Advanced Design System (ADS) software. It includes a graphical user interface (GUI) developed using the design kit feature available under ADS and “Application Extension Language (AEL)” as a programming language. This will extend the existing smart filter design tool under ADS by adding more types of RF filters. The proposed feature will provide to users a rapid and an accurate tool to design and simulate RF filters by presenting interactive menus facilitating the process. As a proof of concept, an application of this tool is presented for the design of a Dual‐Behavior Resonators filter. The tool can be upgraded by adding other RF components and even entire front‐end circuits. In a future step, this tool will be enhanced by adding tuning capabilities to RF filters using ideal capacitors and varactors, which will make it the first one of its kind in the literature.

Cavity resonator-integrated guided-mode resonance filters with on-chip electro- and thermo-optic tuning.

Cavity resonator grating filters (CRIGFs) integrated on lithium niobate on insulator (LNOI) with electrical tuning elements are reported. The resonance wavelength of the filters is in the 780 nm range. Integrated thermo-optical tuning range of 2.5 nm is measured using integrated resistors, whilst a 0.7 nm electro-optical tuning range using capacitive metallic pads is achieved with ±400V drive voltage.

Analytical Approach to Designing a Combined-Mode Resonator Filter on Surface Acoustic Waves Using the Model of Coupling of Modes

Introduction. Bandpass filters are important components that determine the basic characteristics of transmitting and receiving radio electronic equipment. Such filters implemented on surface acoustic waves (SAW) not only demonstrate excellent electrical parameters, but also meet compactness requirements. The relevant research task of reducing the design time and optimizing the filter’s cost can be solved by either using modern computational software or improving existing modeling tools.Aim. To describe the current state and main features of approaches to calculating SAW-based bandpass filters using the model of coupled modes and its formalization based on P-matrices. To describe the main principles and approaches on the example of designing a combined-mode resonator filter on leaky SAW and comparing the calculated and experimental data.Materials and methods. A theoretical study was carried out using the mathematical theory of differential equations presented in a matrix form, as well as the methods of finite element analysis and circuit theory. The results were processed in MatLab and COMSOL.Results. The current state of the analytical approach to designing SAW-based filters using the model of coupled modes and its formalization based on P-matrices was described. An original design for a resonator filter based on leaky SAW at 49° YX-cut of lithium niobate was proposed. The filter has a relative bandwidth of 5.8 %, an insertion loss of –3.7 dB, and a stop-band rejection of –50 dB. A technique for calculating SAW-based filters was proposed.Conclusion. The proposed analytical approach to designing SAW-based bandpass filters allows the filter characteristics (e.g., transmission factor) to be reliably predicted at the modeling stage, thereby reducing the number of experimental iterations and increasing the development efficiency.

Heterogeneously integrated widely tunable laser using lattice filter and ring resonator on Si photonics platform.

We fabricated a tunable laser consisting of a Si lattice filter, a Si ring resonator, and a III-V gain region. The lattice filter, a cascade of interferometers with the same delay length, has periodic transmission peaks with a wide free spectral range (FSR). By connecting the lattice filter to a ring resonator with a narrow FSR, the lasing mode is selected from one of the resonance modes of the ring resonator. The lasing wavelength can be tuned by changing the transmission peak wavelength of the lattice filter, in which an integrated micro heater controls the refractive index of the longer or shorter arm. Since the length of the refractive index control region on both arms of the lattice filter can be extended while maintaining a wide FSR, a wide tuning range can be obtained. This laser facilitates the control of the lasing wavelength because of the simple configuration. The Si lattice filter and the Si ring resonator were fabricated on a Si photonics platform by a Si photonics foundry, and III-V gain region was heterogeneously integrated. The lasing wavelength is shifted to a longer (shorter) one by heating the longer (shorter) arm of the lattice filter, in which the tuning wavelength is 1529 to 1561 nm and side-mode suppression ratio is more than 40 dB. A Lorentzian linewidth for lasing wavelengths narrower than 40 kHz is also demonstrated.