Compact CMOS current conveyor for integrated NEMS resonators

A fully integrated nanoelectromechanical system (NEMS) resonator together with a compact built-in complementary metal-oxide-semiconductor (CMOS) interfacing circuitry is presented. The proposed low-power second generation current conveyor circuit allows measuring the mechanical frequency response of the nanocantilever structure in the megahertz range. Detailed experimental results at different DC biasing conditions and pressure levels are presented for a real mixed electromechanical system integrated through a combination of in-house standard CMOS technology and nanodevice post-processing based on nanostencil lithography. The proposed readout circuit can be adapted to operate the nanocantilever in closed loop as a stand-alone oscillator.     

A miniature dual-band filter based on microstrip dual-mode resonators

A microstrip dual-band bandpass filter (DBF) with an original miniature design is described. The filter consists of thee microstrip dual-mode resonators, which are rendered dual-mode by splitting their regular strip conductors from one end by longitudinal slots. The formation of one passband of the DBF involves the resonances of even modes of each microstrip double-mode resonator, while the other passband is formed by the resonances of odd modes. The proposed device is simple to manufacture and allows the central frequencies and widths of each passband to be tuned within broad limits. A method of DBF tuning has been developed. Good prospects of the proposed microstrip DBF are confirmed by the high characteristics of its working prototype.     

Dual-mode microstrip filters with adjustable transmission zeros

A new type of dual-mode microstrip square-loop resonator that produces asymmetrical frequency responses is proposed. The coupling between degenerate modes of the proposed dual-mode resonator is discussed depending on the perturbation size. The effect of non-orthogonal input/output feed lines located along a straight line on the frequency response is investigated using full-wave electromagnetic simulations. Two second-order bandpass filters using this type of dual-mode microstrip resonator are designed, fabricated and measured to demonstrate the dual-mode microstrip filters exhibiting transmission zero (TZ) shifting property. The one of the second-order filters produces a filter characteristic with two TZs in the upper stopband, whereas the other one has two TZs in the lower and upper stopbands. The shifting property of one of the TZs from one side of the passband to the other side is realised by only changing the perturbation size. The fourth-order filters of this type are also investigated. Both simulated and measured results are presented.     

Resonator/Oscillator response to liquid loading

The resonant frequency of a thickness-shear mode resonator operated in contact with a fluid was measured with a network analyzer and with an oscillator circuit. The network analyzer measures changes in the device's intrinsic resonant frequency, which varies linearly with (ρη)(1/2), where ρ and η are liquid density and viscosity, respectively. The resonator/oscillator combination, however, responds differently to liquid loading than the resonator alone. By applying the operating constraints of the oscillator to an equivalent-circuit model for the liquid-loaded resonator, the response of the resonator/oscillator pair can be determined. By properly tuning the resonator/oscillator pair, the dynamic range of the response can be extended and made more linear, closely tracking the response of the resonator alone. This allows the system to measure higher viscosity and higher density liquids with greater accuracy.     

Modified mason model for bulk acoustic wave resonators

Accurate modeling of a bulk acoustic wave resonator frequency response is limited by the inability of the current 1-D models to simulate certain parasitic modes excited in realistic 3-D structures. A simple technique is proposed to simulate such parasitic modes by employing the 1-D Mason Model of a resonator and a coupling term between the fundamental mode and those parasitic modes. This Modified Mason Model allows accurate simulation of resonators with arbitrary impedance and arbitrary resonating frequency. Finally, the model's prediction is compared with the on-wafer measurement of a ladder-type filter composed of several resonators.     

Analysis of Metamaterial Cloaks Using Circular Split Ring Resonator Structures

A novel microwave cloak using circular split ring resonator (SRR) based metamaterial structure has been proposed in this paper. The cloak which operates at a frequency of 10.6 GHz is composed of cylindrical dielectric sheets printed with circular split ring resonators of spatially varying and anisotropic material properties. The article also focuses on the phenomenon of resonant splitting in circular SRR microwave cloak. A detailed analysis of various linear metamaterial arrays and their response has also been elucidated.     

A method of "weak resonance" for quality factor and coupling coefficient measurement in piezoelectrics

In the absolute-immittance spectrum of a piezoelectric resonator (PR), if the relative resonance-antiresonance frequency interval of a high-intensity resonance is basically determined by the coefficient of electromechanical coupling (CEMC), the relative resonance-antiresonance frequency interval of a low-intensity resonance with the resonance-antiresonance attenuation less than 15 dB, regardless of the reason, is determined by the quality factor Q of the resonance, and its intensity is proportional to the CEMC. The technique for the quality factor and CEMC determination based on the "weak resonance" (WR) concept has been formulated and then applied to low-Q and/or low-CEMC piezoelectrics, including the initial stage of piezoceramics polarization, and to piezotransducers under electrical or mechanical loading with maximum efficiency. The WR method allows one to determine the quality factor on PRs under specific conditions, such as arbitrary PR shape resulting to a broken frequency spectrum; PRs with an extremely large or extremely low electrical capacitance; at high-order PR harmonics; electrodeless piezoelements under mechanically contactless electrical excitation; determining the local thickness-mode material quality factor value and its distribution along the surface of a thin electrodeless piezoplate--all this where the traditional methods show a poor performance or do not work at all.     

Theory of 1- N-way phase-locked resonators

A 1-N-way resonator based on beam splitting and beam combining effects in rectangular cross-sectional multimode waveguides was recently proposed. Such a resonator structure offers a valuable way in which N low-power laser elements may be combined in a coherent fashion. We examine the case of passive 1-N-way resonators. We develop a theory of these 1-N-way structures to show that there is only one possible mode of these resonators. The theory is used to give a scaling law for the design tolerances of the beam splitting and beam combining region of the resonator.     

Analog system-level fault diagnosis based on a symbolic method inthe frequency domain

Concurrently, a symbolic approach for analog system-level fault. Diagnosis and a systematic approach to maximize the fault location capability are proposed. This unified approach is realized as a result of combining the simulation before test (SBT) fault dictionary diagnosis method with a symbolic approach. The traditional SBT fault dictionary method is often costly aid inefficient because of a high number of simulations, but it can become very efficient when a symbolic approach is employed. This symbolic approach only requires one analysis for circuit topology to generate the network transfer function and a parameter substitution to obtain the frequency response (or time response) of the system. An efficient program is developed to deal with the frequency responses of the system to provide the optimum testing point set, and to automatically generate the fault dictionary. The “distance” between the measurement data and the frequency responses from the fault dictionary is evaluated to determine the diagnosis results. A practical example is presented in order to illustrate the main features of this proposed analog system fault diagnosis approach     

A microstrip diplexer based on dual-mode resonators

A miniature third-order microstrip diplexer comprising a traditional T-shaped dual-mode resonator at the input and one dual-mode resonator of original design, with regular strip conductors split from one end, at the output of each channel. The passband formation in each channel of the diplexer involves two resonances of the lowest modes of one split microstrip resonator and the resonance of one of the two modes of the T-shaped microstrip resonator. The proposed device is simple to manufacture and allows the central frequencies and bandwidths in each channel to be varied within broad limits. The good prospects of the proposed microstrip diplexer are confirmed by the high characteristics of its working prototype.     

A SAW resonator with two-dimensional reflectors

It is known that a part of the loss of leaky SAW resonators is due to radiation of acoustic energy in the bus-bars. Many researchers are working on so-called phononic crystals. A 2-D grating of very strong reflectors allows these devices to fully reflect, for a given frequency band, any incoming wave. A new device based on the superposition of a regular SAW resonator and a 2-D periodic grating of reflectors is proposed. Several arrangements and geometries of the reflectors were studied and compared experimentally on 48° rotated Y-cut lithium tantalate. In particular, a very narrow aperture (7.5 ?) resonator was manufactured in the 900 MHz range. Because of its small size, this resonator has a resonance Q of only 575 when using the standard technology, whereas a resonance Q of 1100 was obtained for the new device without degradation of the other characteristics. Because of the narrow aperture, the admittance of the standard resonator showed a very strong parasitic above the resonance frequency, whereas this effect is drastically reduced for the new device. These results demonstrate the feasibility of the new approach.     

Characterizing nonlinear resonant structures

A method for the characterization of nonlinear resonant systems is proposed, which is based on the measurement of the transfer coefficient as a function of the frequency at constant amplitude of oscillations in the resonator. In this case, the amplitude-dependent characteristics of the nonlinear resonator, such as the level of losses and the resonance frequency, are the same for all points of the measured resonance curve. This situation can be realized by carrying out the measurements at a fixed output power. The resonance curve measured using this approach, in contrast to the standard amplitude-frequency characteristic obtained at a constant input power, has a Lorentz shape even for a strongly nonlinear system (irrespective of the operative mechanism of nonlinearity), which allows the Q value to be correctly defined (so that it will be constant for the entire measured resonance curve) and determined. The proposed method is illustrated by measuring the characteristics of a superconducting filter in a nonlinear regime.     

Dielectric-Parameter Measurements of SiC at Millimeter and Submillimeter Wavelengths

High-precision continuous spectra of the absorption coefficient, refractive index, complex dielectric permittivity, and loss tangent for several silicon carbide (SiC) specimens are reported in this paper over a broad millimeter- and submillimeter-wave range for the first time. Measurements have been successfully performed using three different types of specially constructed spectrometer systems: a dispersive Fourier transform spectroscopy, an automated 60-GHz open resonator, and a free-space quasi-optical millimeter-wave spectrometer equipped with high-power backward-wave oscillator sources and their associated state-of-the-art dielectric-measurement techniques. Data are presented as continuous functions of frequency from 30 to 600 GHz. The employment of various measurement systems and techniques ensured the measurement of polycrystalline SiC specimens with various degrees of absorption and dispersion characteristics over an extended frequency range with high precision. Results presented here provide comprehensive information of SiC on its optical and dielectric behavior as a function of frequency and purity for its potential application in semiconductor and radio-frequency devices and circuits. An error analysis of measured dielectric-parameter results is also provided.     

耦合共振型进气消声器声学特性分析

为了拓宽消声频带、提高消声量,克服传统串并联腔体结构安装空间大等缺点,研究了一种新型耦合共振型进气消声器．利用一维平面波理论探究了Helmholtz消声器的消声机理;为准确模拟消声器突变结构处的高阶次声波,建立了并联共振腔结构和新型结构Helmholtz消声器的声学有限元计算模型;计算、分析、比较了各结构的消声特性,重点研究了新型结构尺寸参数对其共振频率与传递损失的影响．计算结果表明：由于腔体间空气耦合共振作用,两腔耦合共振型Helmholtz消声器具有3个共振频率;两共振腔连接管的长度与直径是影响该结构消声性能的关键尺寸,减小连接管长度或者增大直径都可以拓宽消声器的消声频带,提高消声性能．这将为主动、被动耦合共振型进气消声器的设计提供重要参考．     

Design of a compact dual-mode ring resonator bandpass filter with harmonic suppression

Abstract

An approach to suppress the harmonic responses in a dual-mode circular ring resonator bandpass filter is presented. Feed lines with one-sided coupling arms are suitably relocated around the ring resonator to introduce phase interference between two degenerate modes for simultaneously suppressing the second and third harmonics. Three open loop resonators at the rim of the ring are adopted to further suppress the second harmonic. By fabricating on a FR4 glass-epoxy base, this approach is demonstrated to have effectiveness in broadening the filter's rejection band in both simulations and measurements without affecting the fundamental response or increasing the device size.     

An Automatic Digital Q-Meter: New Approach to the Digital Measurement of Magnification Factor

Few procedures, known so far, for the design of a digital Q-meter, were based on the ratio between the reactive and the nonreactive components of measured circuit elements or on the determination of the corresponding logarithmic decrement in that circuit. In the first procedure, the ratio of two voltages, proportional to the above mentioned components, has to be found and numerically displayed, when the same current passes through these components. This procedure is limited to relatively low frequencies and hence to small values of a Q-factor. In the second procedure, the number of damped oscillations in the circuit with the tested elements, which occur in the time interval between the initial amplitude of a suddenly injected signal and the damped amplitude e? time smaller than the first one, corresponds to the numerical value of the Q-factor. The new procedure, presented in this paper, results in the numerical display of the Q-factor of an oscillatory circuit (or of its self-inductive element) at a relatively high resonant frequency. The procedure is based on the determination and numerical display of the ratio between the overvoltage, created by the resonance, and the high-frequency voltage injected in the oscillatory circuit. During the sweeping of the frequency-modulated injection signal around the proposed resonant frequency, the differentiation of the corresponding resonance curve is made; the passage of the differentiated signal through the zero value is marked by an appropriate comparator circuit.     

半球谐振子超精密修调方法研究

目的 研究因谐振子质量缺陷而引起的频率裂解机制,进而对刚性轴位置进行质量高分辨率可控去除,提高陀螺精度。方法 首先基于多区域配合划分法建立半球谐振子高精度有限元仿真模型,分析质量大小与位置对谐振子频差的影响规律。其次搭建谐振子振动特性检测平台,利用拍频法实现其频差值和刚性轴位置的精确辨识。最后结合仿真与辨识结果以及离子束加工方法确定谐振子超精密修调方案。结果 优化网格划分方法后,谐振子有限元模型频差值小于0.000 1 Hz,当修调定位误差相同时,在一个范围内的质量去除比单点质量去除的修调效率更高;谐振子质量缺陷四次谐波刚性轴位置辨识精度可达0.1°,与常见的幅值法相比,其精度提高了一个数量级;通过三次点线结合方式进行质量修调后,谐振子频差值小于0.001 Hz,修调效率与精度得到了提升。结论 提出的谐振子仿真模型、振动特性测试方法以及离子束修调工艺精度较高且可行性较强,对实现半球谐振子性能高精度检测以及高质量加工具有重要意义。     

Microwaves Interaction Peculiarities with the Ideal Gas of Alkali Atoms in BEC State

We represent a theoretical approach that is based on approximate formulation of the second quantization method at low temperatures. It allows to study a system consisting of alkali atoms response to the perturbation by the external electromagnetic field. We show that such approach is convenient to study the propagation properties of microwave signal, tuned up to the transition between hyperfine ground state levels of alkali atoms that are considered in Bose-Einstein condensation (BEC) state. The phenomenon is studied in case of hyperfine levels Zeeman splitting. The dependence of pulse slowing on the system parameters is found. It is shown that a slowed signal can propagate in such system with rather small energy loss. A possibility to observe ultra-slow microwaves in the condensed gas of cesium atoms is discussed.      

New method of determining the Q-factor of quartz-crystal resonators

Conclusions The measurement error of the above method does not depend on the Q-factor of the quartz resonator nor on its frequency, which makes it applicable in any frequency or Q-factor range, whereas other methods are restricted in their application either by their minimum decay time or by their minimum bandwidth. Knowing the Q-factor, the equivalent resistance and the frequency of the quartz resonator, it is possible to calculate its equivalent inductance and dynamic capacitance. Thus, the above circuit makes it possible to determine all the parameters of a quartz resonator equivalent circuit. Translated from Izmeritel'naya Tekhnika, No. 11, pp. 50–51, November, 1961