Adaptive 1-D and 2-D Filtering with Internally Passive Structures

Internally passive filters such as wave digital filters (WDF) and orthogonal filters, which have desirable properties, are developed as filter structures for adaptive filters. The equations for updating the multiplier coefficients as well as for computing the gradients are derived for these filters. The stability monitoring during the adaptation process for these filters is simple to implement. Simulation results are included to demonstrate the capability of these filters in system identification and noise cancellation. Moreover, motivated by applications of multidimensional adaptive filters in video compression and image enhancement, the proposed adaptive wave digital filters have been extended to two dimensions and applied as adaptive fan filters. Computer simulations are also conducted to show their potential applications to two-dimensional system identification and image enhancement.     

On the Elimination of Reactive Element Loops and the Use of Special Approximations in the Design of OTA-C Filters

Loops of reactive elements in passive filters cause a series of problems in OTA-C simulations of these structures. These loops can be eliminated in a systematic way by the procedures described in the paper. The use of special approximations in the design of the passive prototype filters allows the elimination of multiple loops of reactive elements that appear in usual LC ladder filters with finite transmission zeros. This leads to more efficient active simulations, where problems with floating capacitors, DC or high-frequency instability, or limited operating frequency are avoided.     

A practical method of coefficient computation for a microprocessor-controlled variable recursive digital filter

The synthesis of general-type recursive digital filters from analog prototypes may require complicated computations not suitable for filter structures where the coefficients are to be evaluated by a microprocessor control unit. A general synthesis procedure suitable for the application to such structures is described and some design examples are reported.     

甚宽带PBG滤波器结构

研究了光子带隙结构作为微带电路衬底的情况,分析其阻带特性的形成以及对电路性能的影响.提出了利用级联与混合并联结构设计具有很宽频带的滤波器形式.实验测量了其传输特性,验证了频率阻带的存在和作为宽带滤波器结构的可行性.     

重叠写入啁啾光纤光栅型滤波器的研究进展

高性能的波分复用器是密集波分复用系统的核心器件之一,重叠写入啁啾光纤光栅型带通滤波器充分发挥了光纤光栅优良的波长选择特点,是一种低成本的新型全光纤波分复用器件.综合评述了各种不同结构的重叠写入啁啾光纤光栅型滤波器的工作原理、基本特点及其应用.     

Cascade realization of linear phase fir filters with low sensitivity

The errors due to coefficient quantization in a digital filter are sensitive functions of its pole and zero locations. In this paper, a detailed analysis is made of the sensitivity, with respect to the location of zeros, of elemental fourth-order sections, for cascade realization of linear phase FIR filters. New structures are suggested for the realization of the sections with low sensitivity. Performance analysis of these structures in implementation of a few representative filters indicates their suitability for practical applications.     

Non-symmetric lattice structure for pole zero filters

This communication generalizes the lattice structure of IIR digital filters and shows its relation with classical structures. The algorithm for computing the corresponding reflection coefficients is given. It is also shown that this algorithm computes the greatest common divisor of the numerator and the denominator of the transfer function.     

RF-MEMS谐振器和滤波器研究进展

介绍了基于梳状、梁式、圆盘三种结构的射频微机电系统( RF-MEMS)谐振器及滤波器,并对RF-MEMS谐振器及滤波器的结构与性能参数进行讨论;分析RF-MEMS谐振器及滤波器设计和制造中的有关问题及其处理方法;RF-MEMS谐振器及滤波器性能优异,能与其他器件实现片上集成,且与集成电路工艺兼容,在射频无线通信系统中的...     

Prediction Capabilities of Boolean and Stack Filters for Lossless Image Compression

This paper proposes optimal Boolean, stack, and FIR-Boolean hybrid filters for realizing the prediction stage in lossless grey-level image compression. New optimal design procedures for Boolean filters are introduced, where the optimality criterion is the Error Entropy (EE). The use of the EE-optimal and MAE-optimal Boolean and stack filters in the sequential prediction structure is considered, under different instances: global-optimal, block-optimal, adaptive-size-block-optimal and multiresolution. An extensive simulation study is carried out for analyzing and comparing the performances of the newly introduced predictors and various other sequential predictors. The EE-optimal Boolean predictors prove to be the most efficient predictors. More refined filtering structures, such as block-optimal or adaptive-size-block-optimal are suitable for the prediction task when the prediction mask ought to be small. The proposed progressive transmission structure based on optimal Boolean prediction is shown to outperform HINT HINT progressive lossless coding scheme.     

Synergy at work between continuous-time and sampled-data analog filters for integrated high-frequency,high-Q signal processing

High-frequency, high-Q-factor analog signal processing systems based on sampled-data switched-capacitor circuitry and continuous-time filters are proposed in a way that tends to combine the most advantageous aspects of both techniques. The new systems are applicable to video, radio and radar filtering functions and have unparalleled potential for producing more accurate, economical, and repeatable results than have been achieved with other methods.1.F _s is the sampling frequency and M and L are integers.2. A similar model could easily be established for the complementary frequency upconversion operation following the SC filter and involving the SC interpolator and the output CT filter, but this will not be considered here for conciseness.     

On sub-ideal causal smoothing filters

Smoothing causal linear time-invariant filters are studied for continuous time processes. The paper suggests a family of causal filters with almost exponential damping of the energy on the higher frequencies. These filters are sub-ideal meaning that a faster decay of the frequency response would lead to the loss of causality.     

关于耦合谐振滤波器中耦合极性的几点讨论

对改变带有交叉耦合的耦合谐振滤波器中的耦合系数的极性而不改变滤波器的性能 ,本文给出了一个充分条件及其两个推论。这为滤波器的设计和实现带来了一定的灵活性。结合这一充分条件 ,本文还详细解释了滤波器中的耦合极性的相对性问题。最后给出了在确定耦合系数矩阵后实现滤波器时设计耦合结构的一种通用方法。     

Announcements and calls for papers

The stability of recursive time-variant digital filters depends on the variable filter coefficients as well as on the chosen state-space structure. A condition for the behaviour of the state vector is given, that guarantees asymptotic stability in the sense of Lyapunov. Some structures do always yield this behaviour. However, all other structures produce the same output signal with a suitable transformation of the state vector with every coefficient change. This transformation can be implemented without increase of the computational complexity when the filter coefficients are altered. This will be demonstrated by an example for a structure with the minimum number of multipliers.     

A Method to Reconstruct Nth-Order Periodically Nonuniform Sampled Signals

A continuous time signal x(t) with Fouriertransform X(v) band-limited to ?ω /2相似文献   

双模曲折悬置带线环四极微波滤波器

该文研制了双模曲折悬置带线环四极微波滤波器。采用全波技术对该种滤波器特性进行的计算表明,它具有优良的窄通带、高选择性和小体积,与同类型二极滤波器相比,过渡带更陡峭。采用优化设计方法设计出了滤波器电路尺寸,制造了以r=2.8的Teflon为介质基片的滤波器,测试得到的双模曲折悬置带线四极滤波器的中心频率为f0=1.194 GHz,△f=19.4 MHz,通带插入损耗LP4.3 dB,阻带衰减Ls50 dB,实验结果和CAD预测作了比较,两者基本一致。这种滤波器可望在多种微波系统和移动通信系统中应用。     

Capacitorless digitally programmable fractional-order filters

Novel topologies of fractional-order filters, implemented using the internal gate-source capacitance of MOS transistors, are introduced in this paper. This has been achieved using current-mirrors as active elements, resulting into resistorless realizations due to the employment of the small-signal transconductance parameter of the MOS transistor. This also offers the capability for electronic tuning of the frequency characteristics of the derived filter structures. The evaluation of the proposed technique has been performed through the design of a generalized fractional-order filter, which is also digitally programmed in such way that the four standard filter functions are offered. The behavior of the filter has been evaluated using the Cadence IC design suite and the Design Kit provided by the Austrian Micro Systems 0.35 μm CMOS process.     

Deterministic properties of separable and cross median filters with an application to block truncation coding

In this paper, we present some deterministic properties of separable and cross median filters. It is proved that in the absence of vertical binary oscillations, the roots of a separable median filter are included in a subset of root signals of the corresponding cross median filter. Moreover, the sufficient and necessary condition is given for a point to be invariant to cross median filtering. On the root structures of cross median filters, we indicate that there exist three different types of regions based on the one-dimensional features of rows and columns. Finally, an application example is discussed where the roots of separable and cross median filters are used in block truncation coding (BTC) for image compression.     

908厂早期高效空气过滤器

介绍中国早期高效空气过滤器制造过程。原苏联提供了全套图纸和工艺文件,908厂利用国产材料研制出高效过滤器。1961年研制成功并批量制造第一批高效空气过滤器。1981年停止了老型号产品的生产。     

Miniature and tunable millimeter-wave lowpass filter with MEMS switch

In this paper, fully monolithic tunable millimeter-wave filters with tapped-line feedings are proposed using the CPW-based periodic structures with novel multiple-contact MEMS switches. Millimeter-wave low-pass filters were designed, fabricated, and tested. The cascaded CPW-based periodic structures, with low-pass intrinsic filtering characteristics, are reconfigured into a self-similar single unit cell by the operation of the novel multiple-contact MEMS switches with single actuation. The measured results of the reconfigurable low-pass filter show the 3-dB cutoff frequency change from 19 to 11 GHz with very small change in the average insertion loss from 1.3 to 1.9 dB. The chip size of the low-pass is 4.0 mm × 1.6 mm.     

Implementation of 2-D denominator-separable digital filters using first-order all-pass sections

It is established that denominator-separable transfer functions which characterize an important subclass of 2-D filters can be expressed as a linear combination of first-order (1-D or 2-D separable) all-pass transfer functions with real or complex coefficients. This type of expansion is referred to as all-pass expansion of the corresponding transfer function. Based on this all-pass expansion, we derive some efficient structures for the realization of 2-D denominator-separable filters using all-pass sections.On leave from S.V. University College of Engineering. Tirupati-517502, India.