K-band MMIC active band-pass filters

Two K-band active band-pass filters using 0.15-/spl mu/m GaAs pHEMT technology, with one fixed-frequency and the other tunable, are designed, fabricated, and tested. The fixed-frequency filter has its central frequency at 22.6 GHz, with 900-MHz bandwidth (4%). The tunable filter can be tuned from 19.5 to 21.5 GHz with the same bandwidth. Both circuits have a common size of 1 mm /spl times/ 1 mm. To our knowledge, the tunable filter is the highest frequency tunable active filter ever reported.     

Design of active transimpedance band-pass filters with different Q values

Transimpedance filter is a filter which realises a transimpedance transfer function. In this article, the design methods for the transimpedance band-pass filter are presented. The circuit topologies and parameter calculation formulas of three bi-quadratic transimpedance band-pass filter topologies with low-, medium- and high-Q values are proposed, respectively. A high-order transimpedance filter can be obtained by realising a bi-quadratic transimpedance filter first and then cascaded with voltage-mode bi-quads. A high-order transimpedance filter design example is given; the simulation and the measured results verify the effectiveness of the proposed transimpedance filter design method.     

Design of active transimpedance band-pass filters with different Q values

Transimpedance filter is a filter which realises a transimpedance transfer function. In this paper, the design methods for transimpedance band-pass filter are presented. The circuit topologies and parameter calculation formulas of three bi-quadratic transimpedance band-pass filter topologies with LQ, MQ and HQ are proposed respectively. High order transimpedance filter can be obtained by realising a bi-quadratic transimpedance filter first and then cascaded with voltage mode bi-quads. A high order transimpedance filter design example is given, the simulation and the measured results verify the effectiveness of the proposed transimpedance filter design method.     

基于FilterLab2.0的一种有源窄带滤波器的设计

在无线通信的一些特殊场合中,需要窄带选频放大.常用的滤波器仿真软件都不能做窄带有源滤波电路的仿真.本文在软件仿真的基础上,通过实验验证并对电路改进,设计出了一种低噪声、低功耗、中心频率为800HZ的窄带有源滤波电路.采用OP482G构建电路,实验结果表明该电路可以具有很高的Q值.     

Microwave active filters based on coupled negative resistancemethod

A novel coupled negative resistance method for building a microwave active bandpass filter is introduced. Based on this method, four microstrip line end-coupled filters were built. Two are fixed-frequency one-pole and two-pole filters, and two are tunable one-pole and two-pole filters. In order to broaden the bandwidth of the end-coupled filter, a modified end-coupled structure is proposed. Using the modified structure, an active filter with a bandwidth up to 7.5% was built. All of the filters show significant passband performance improvement. Specifically, the passband bandwidth was broadened by a factor of 5 to 20     

Surface-acoustic-wave resonator filters

This paper presents an overview of surface-acoustic-wave (SAW) resonator filter technology. Given the current state of the art, these filters promise reproducible low-loss (≲6 dB) narrow-bandwidth (500 ≲ f/Δf ≲ 50 000) responses in the VHF and UHF ranges. Devices that contain one or a number of sections, each consisting of a resonant cavity between two grating reflectors and an input and output coupling mechanism, are considered. The initial discussion describes the layout, theoretical characteristics, and typical experimental responses of singlesection two-port filters. The subsequent discussion focuses on multisection devices using any of various intercavity coupling techniques. A generalized analysis and design formalism based on wave-scattering theory is reviewed, and experimental results from a number of device prototypes are given. Finally, practical design and fabrication trade-offs and performance ranges are summarized for a number of configurations.     

Tunable microwave and millimeter-wave band-pass filters

The authors present an overview of tunable microwave and millimeter-wave bandpass filters realized in different technologies. Some general design principles are described. Recent progress in the performance of various tunable filters is reported. The authors survey magnetically tunable filters (ferrimagnetic resonance filters, magnetostatic-wave filters, evanescent waveguide filters, E-plane printed circuit filters), electronically tunable filters, and mechanically tunable filters. The typical performance parameters are summarized. This comparison shown that none of these devices can simultaneously satisfy all requirements for perfect tunable filters. For microwave systems where multioctave tuning is essential, a YIG filter is an obvious choice. In systems where the requirement of high power handling capability combined with low insertion loss, predominates, mechanically tunable filters and magnetically tunable E-plane filters are recommended. If the tuning speed is a crucial requirement, varactor-tuned filters or E-plane filters with ferrite toroids are devices of choice. For millimeter-wave design, the most promising structures are ferrimagnetic resonance filters utilizing hexagonal ferrite resonators or, up to 60 GHz, magnetically tunable E-plane printed circuit filters     

Passive CCD resonator filters

Novel passive recursive CCD bandpass filters have been realized using standard two-level-polysilicon gate NMOS technology. A Chebyshev bandpass (w/SUB rel,/ /SUB 3/ /SUB dB/=3.1 percent) and a fully integrated CCD signal filter with an extremely narrow 3 dB bandwidth of 97 Hz (Q=1350) at 131.85 kHz center frequency were implemented by means of cascaded CCD resonators. The latter chip contains the necessary clock generation and biasing circuitry realized with dynamic circuit techniques to achieve low power consumption (40 mW per filter). Performing all filtering operations exclusively in the charge domain ensures filter passivity. An extremely stable center frequency and a bandwidth independently controlled by a capacitance ratio are the special advantages of such filters.     

高阶带通滤波器设计研究

本文详细讨论了FIR线性相位滤汉器幅频特性与神经网络算法之间的关系,证明了神经网络的收敛性条件,给出了FIR高阶带通滤波器的设计实例,研究结果表明该算法在高阶带通滤波器的优化设计中的有效性和优异性能。     

Electrically cascaded surface-acoustic-wave resonator filters

Three nearly identical surface-acoustic-wave resonator filters at ? 35 MHz have been fabricated with aluminium metallisation on yz LiNbO3 substrates. The filters are electrically cascaded to yield a combined frequency response that exhibits 80 dB sidelobe suppression, Q ? 3000, no spurious responses in the range 1?500 MHz and an insertion loss in a 50 ? system of only 13 dB.     

Microring resonator channel dropping filters

Microring resonators side coupled to signal waveguides provide compact, narrow band, and large free spectral range optical channel dropping filters. Higher order filters with improved passband characteristics and larger out-of-band signal rejection are realized through the coupling of multiple rings. The analysis of these devices is approached by the novel method of coupling of modes in time. The response of filters comprised of an arbitrarily large dumber of resonators may be written down by inspection, as a continued fraction. This approach simplifies both the analysis and filter synthesis aspects of these devices     

New dual-mode dielectric resonator filters

The paper presents a new design of dual-mode dielectric-loaded rectangular cavity filters. The response of the filter is mainly controlled by the location and orientation of the coupling apertures with no intra-cavity coupling. Each dual-mode dielectric-loaded cavity generates and controls one transmission zero which can be placed on either side of the passband. Example filters which demonstrate the soundness of the design technique are presented.     

10 Gbit/s timing recovery circuit using dielectric resonator and active bandpass filters

A clock recovery circuit that employs a dielectric resonator, designed for the 10.368 Gbit/s demonstrator of the R1051 RACE project is described. Experimental results have shown a jitter performance and sensitivity to detuning well within usual specifications for practical links. This circuit thus provides a very attractive low cost solution for multigigabit transmission.<>     

Automated CAD of coupled resonator filters

A gradient-based optimization technique along with a new definition of cost function is applied to the CAD of coupled resonator filters. The topology of the structure is enforced at each step of optimization and its physical dimensions are used as optimization variables. The cost function is defined using location of zeros and poles of the filter's transfer and reflection functions. Numerical tests show that with the new definition of the cost function, the optimization process converges from an arbitrarily selected starting point. This allows one to design filters even without a rough microwave synthesis which usually provides initial dimensions.     

Miniature high-Q double-spiral slot-line resonator filters

A new class of low insertion-loss miniaturized filters using slot-line resonators is proposed. Miniaturization is achieved by terminating the slot line with a double-spiral inductive termination at both ends. Using this miniaturized resonator, both positive and negative couplings may be realized, and therefore, both standard coupled-line and cross-coupled quasi-elliptic filters are realizable. The unloaded Q of these slot-line filters is considerably higher than that of miniaturized microstrip filters of comparable dimensions due to the inherent higher Q of the slot line. To demonstrate the validity of the design procedures and the performance characteristics, two different types of filters were fabricated and tested. One is a four-pole Chebyshev filter and the other is a quasi-elliptic filter where, in each case, the full-wave simulations show very good agreement with measurements.     

Dielectric resonator filters with wide stopbands

Dielectric resonators used in filter networks present a model spectrum with undesired, or spurious, resonances in close proximity to the desired one. Through the use of evanescent mode bandpass irises tuned to the filter center frequency, the resonator spurious modes are suppressed, resulting in N-section filters with stopbands clean to at least (N-1) times the individual iris stopband levels. The problem of achieving a wide stopband is reduced to the problems of realizing the resonating capacitance required in an evanescent bandpass filter and computing the junction susceptance occurring at the interface between a larger evanescent section (the resonator enclosure) and the smaller iris opening. The technique results in high-Q resonator filters with stopbands clean to at least -55 dBc, out to at least 1.7 times the filter center frequency     

Conductor-loss limited stripline resonator and filters

We report on stripline resonators on thin dielectric membranes that show dispersion-free, conductor-loss limited performance at 13.5 GHz, 27.3 GHz, and 39.6 GHz. The unloaded-Q (Q_u) of the resonators increases as √f with frequency and is measured to be 386 at 27 GHz. The measured results agree well with a new conformal mapping analysis. The stripline resonators are used in a micromachined state-of-the-art planar interdigitated bandpass filter at K-band frequencies. Excellent agreement has been achieved between the microwave model at 850 MHz and the 20 GHz filter. The micromachined filter exhibits a passband return loss better than -15 dB and a conductor-loss limited 1.7 dB port-to-port insertion loss (including input/output CPW line loss) at 20.3 GHz     

Two-path cutoff waveguide dielectric resonator filters

The authors propose an evanescent-mode wave-guide filter consisting of two parallel cutoff waveguide paths with dielectric resonators. They introduce an accurate design method incorporating both the full-wave analytical method and the impedance inverter method. The specified overall characteristic is then synthesized with the help of a computer-aided design method. Measurements on several kinds of filters modeled at X-band show excellent agreement with the designed characteristics     

Direct-coupled resonator filters with improved selectivity

A method is outlined whereby a narrow-band direct-coupled resonator filter may be derived from an elliptic-function low-pass prototype. The construction and performance of a three-resonator waveguide cavity filter designed on this basis is described.