Radial-Line Coaxial Filters in the Microwave Region

Design techniques and a simple empirical formula for the design of band rejection radial-line coaxial filters are presented. The appropriateness of these filters for parametric work is discussed and a particular structure employing these filters to provide a high performance harmonic filter structure for rectangular waveguide is presented.     

Integrated-optic acoustically-tunable filters for WDM networks

The background needed to understand the integrated-optic collinear acoustically tunable optical filters (ATOFs) and the fabrication and performance of both simple and multielement acoustooptic tunable filters is presented. The most important sources of crosstalk between channels simultaneously selected by a single device are discussed. ATOFs have the combined virtues of narrow passband (subnanometer bandwidth), broad tuning range (hundreds of nanometers have been demonstrated), and simultaneous independent multiple-channel filtering. The theory and practice of collinear integrated optic acoustooptic filters is presented. Devices which involve higher-order integration are discussed, including multiple-state filters for enhanced sidelobe suppression and polarization-independent configurations. Various sources of interchannel crosstalk are derived and demonstrated in multiwavelength filtering experiments     

Generalisation of m.f.m.b.o. and transitional Butterworth-Cheby?shev filters

The maximally flat magnitude beyond the origin is generalised to give filters having a controlled passband characteristic. The Cheby?shev polynomials are then used as the variable for these generalised approximants to yield the transitional Butterworth-Cheby?shev filters. Optimisation of these filters is also discussed.     

Design criteria for video sampling rate conversion filters

The design of video sampling rate conversion filters is discussed. It is demonstrated that for such filters to produce a satisfactory picture quality at the new sampling rate, further constraints on the frequency response of the filters are required than have previously been published.<>     

Microwave Filters--1965

A review of recent and current work on microwave filters is presented, and an extensive bibliography of recent articles is appended. The review is largely qualitative and pictorial, rather than mathematical. Among the microwave filter topics discussed are band-pass filters with cascaded lifes or cavities; band-pass and band-stop filters with stubs and parallel-line coupling; low-pass and high-pass filters; the connection between dissipation loss, group delay, and power-handling capacity; delay equalizers; diplexers; directional filters; tunable filters, especially magnetically tunable filters; dielectric-resonator filters; filter techniques applied to semiconductor devices; the connection between filters and directional couplers; filters with open walls; and filters for millimeter waves and higher frequencies.     

Transversal filtering using charge-transfer devices

Techniques are presented for making transversal filters using charge-coupled devices and bucket-brigade devices. In a CCD transversal filter, the delayed signals are sampled by measuring the current flowing the clock lines during transfer, and the sampled signals are weighted by a split electrode technique. In a BBD transversal filter, the delayed signals are `tapped' with a source follower whose load determines the weighting coefficient. Examples are given of CCD and BBD filters that are `matched' to particular signalling waveforms, and the limitations of charge-transfer devices in matched filtering applications are discussed. Finally, the application of CTD transversal filters to other signal processing functions is discussed.     

Crystal, ceramic, and mechanical filters in Japan

In Japan, there has been considerable activity in the research and manufacturing of quartz crystal filters, ceramic filters and mechanical filters. This paper reviews some of these contributions. An emphasis is placed on filters actually used. First multiple-mode resonators are reviewed; this concept having had profound effects on all types of filters. Quartz-crystal filters as well as other crystal filters are discussed. Then follow reviews on ceramic and mechanical filters.     

Vector median filters

Two nonlinear algorithms for processing vector-valued signals are introduced. The algorithms, called vector median operations, are derived from two multidimensional probability density functions using the maximum-likelihood-estimate approach. The underlying probability densities are exponential, and the resulting operations have properties very similar to those of the median filter. In the vector median approach, the samples of the vector-valued input signal are processed as vectors. The operation inherently utilizes the correlation between the signal components, giving the filters some desirable properties. General properties as well as the root signals of the vector median filters are studied. The vector median operation is combined with linear filtering, resulting in filters with improved noise attenuation and filters with very good edge response. An efficient algorithm for implementing long vector median filters is presented. The noise attenuation of the filters is discussed, and an application to velocity filtering is shown     

A compound high-order polarization-independent birefringence filter using Sagnac interferometers

Polarization-independent fiber-optic filters are presented that replace the polarizers in traditional birefringence filters with a Sagnac interferometer. The performance of these filters is discussed when Solc and Lyot type birefringence combinations are used. A high-order, compound filter combining these two filters is presented, along with experimental verification.     

Continuous-time MOSFET-C filters in VLSI

The desirable features of fully integrated, VLSI-compatible continuous-time filters are discussed. A recently proposed integrated continuous-time filter technique is reviewed, in which MOS transistors are used in place of resistors along with the nonlinearity cancellation and on-chip automatic tuning. The filters obtained using this technique are compared to switched-capacitor filters, digital filters, and continuous-time filters using different techniques. Representative experimental results are given, demonstrating the high performance that can be achieved.     

Hairpin-Line and Hybrid Hairpin-Line/Half-Wave Parallel-Coupled-Line Filters

A new class of microwave filters, hairpin-line and hybrid hairpin-line/half-wave parallel-coupled-line filters, is reported. This class of filters is particularly well suited for microstrip and TEM printed-circuit realizations because grounding of the filter resonators is generally not required. Hairpin-line filters have been divided into two types. The first (Type A) is characterized by having its input and output lines open-circuited at their ends. The Type A filter has been found to yield practical impedance levels for narrow to approximately 25-percent bandwidths. The second (Type B) is characterized by having its input and output lines short-circuited at their ends. However, because of space limitations, details of the Type B filter are not presented in this paper. Theoretical background and design equations for Type A bandpass filters are presented. Experimental data for several stripline filters of 5- and 20-percent bandwidths are given. Experimental results for two microwave-integrated-circuit (MIC) filters are discussed.     

Design of microwave filters

A survey of the major techniques used in the design of microwave filters is presented in this paper. It is shown that the basis for much fundamental microwave filter theory lies in the realm of lumped-element filters, which indeed are actually used directly for many applications at microwave frequencies as high as 18 GHz. Many types of microwave filters are discussed with the object of pointing out the most useful references, especially for a newcomer to the field     

Implementation of Digital Unbiased FIR Filters with Polynomial Impulse Responses

This paper addresses the design and implementation of digital unbiased finite impulse response (FIR) filters with polynomial impulse response functions. The transfer function, its fundamental properties, and a general block-diagram are discussed for the impulse response represented with the l-degree Taylor series expansion. As a particular results, we show a fundamental identity uniquely featured to such filters in the transform domain. For low-degree impulse responses, the transfer functions are found in simple closed forms and represented in compact block-diagrams. The magnitude and phase responses are also analyzed along with the group delays. A comparison with predictive FIR filters is given. As examples of applications, filtering of time errors of local clocks is discussed along with the low-pass filter design employing a cascade of the unbiased FIR filters.     

Microelectronic switched capacitor filters

An explanation of what switched-capacitor (SC) filters are and how they work is given. Attention is focused on low-sensitivity SC filters, which can be developed from a general passive ladder where the branches are arbitrary impedances. The equations that describe the filter components are reviewed, and the characteristics of these low-sensitivity filters are outlined. Applications of the filters in telecommunications are discussed     

Inductorless bandpass filters

The technique of designing inductorless filters by replacing the inductors in conventional LC filters with gyrators and capacitors is considered for the special case of the high-quality channel bandpass filters used in multiplex telephony. One particular gyrator circuit, which has been found to be very satisfactory, using two operational amplifiers and four resistors, is analyzed in some detail. The difficulties of simulating floating inductors are discussed, and ways of designing filters to avoid the necessity of such simulations are proposed. The dynamic range of a filter is defined and the factors controlling it are described. Detailed measured results of two specific channel filter designs are included.     

小型射频LC低通滤波器设计

研究射频LC低通滤波器的设计，通过仿真计算研究了以螺旋电感和平板电容作为基本元件的滤波器设计制作在不同介电常数的介质基板上时性能的变化情况，结果表明采用高介电常数的介质基板时滤波器的尺寸可以减小，同时性能指标也可以获得一定的改善。     

一种新颖的PBG宽阻带低通滤波器

 本文首次提出综合PBG结构和微带线结构两因素,来设计滤波器的概念.与普通PBG结构滤波器不同的是,本文采用具有T形和十字形短截线的微带线代替直线微带线,在接地板上只需刻蚀一列PBG结构即可构成宽阻带低通滤波器.文中以T形短截线PBG结构的低通滤波器为例,运用时域有限差分法(FDTD),分析了在不同短截线长度和PBG结构方孔边长的情况下,该滤波器的传输特性.文中还给出了该滤波器和Rumsey方法与Kim方法设计的级联、并联两种PBG结构低通滤波器的传输特性的模拟结果及其对比分析.最后,文中给出了模拟结果和测试结果,来验证所设计的低通滤波器的有效性.     

神经网络在4型FIR滤波器的优化设计研究

本文详细讨论了4型线性相位滤波器幅频特性与正弦基神经网络算法间的关系，提出并证明了该算法的收敛定理，给出了FIR高通滤波器和FIR带通滤波器优化设计实例。计算机仿真结果表明，该算法在FIR高通滤波器和带通滤波器的有效性和优异性能。     

Generalized multistage median filters.

As an extension of the multistage median filters, a class of r -filters is presented. Some properties of these filters are discussed. It is shown that the filters can smooth noise and preserve details of images efficiently.     

A floating-point arithmetic error analysis of direct and indirectcoefficient updating techniques for adaptive lattice filters

The ways in which finite precision arithmetic effects can deleteriously manifest themselves in both the stochastic gradient and the recursive least squares adaptive lattice filters are discussed. closed form expressions are derived for the steady-state variance of the accumulated arithmetic error in a single adaptive lattice coefficient using a floating-point stochastic arithmetic error analysis. The analytical results show that the performance of adaptive lattice filters using a direct updating computational form is less sensitive to finite precision effects than that of adaptive lattice filters using an indirect updating computational form. In addition, a method for reducing the self-generated noise is presented. Experimental results obtained on a 32-b floating-point hardware implementation of the adaptive lattice filters and with computer simulations are included to verify the analytical results describing the effects of finite precision on adaptive lattice filters