A design technique for transitional butterworth-Chebyshev filters

For most of the given filter orders, the design technique reported recently [1] can generate neither a complete nor a gradual transition of filters between the Chebyshev and Butterworth extremes. An alternative design is proposed here without such difficulties.     

Transitional MURROMAF-MURROER filters with additional members

Recently, a method [4] has been described for the design of transitional MURROMAF-MURROER filters whose members exhibit odd numbers of passband ripple peaks. An additional technique is proposed here to find also those with even numbers of the ripple peaks. Hence, transitional MURROMAF-MURROER filters with complete transitional members.     

Direct design of transitional Butterworth-Chebyshev recursive digital filters

A simple method for the approximation of an all-pole transfer function directly in the digital domain for the design of recursive digital filters is described. The transfer function of these filters, referred to as transitional Butterworth-Chebyshev filters, has properties that lie between Butterworth and Chebyshev functions.<>     

On transitional ultraspherical-ultraspherical filters

A generalization of the transitional Butterworth-Chebyshev filter is presented. Using this method, at least ten different types of transitional filters can be obtained.     

All-pole transitional Bessel-Chebyshev filters

A new family of all-pole equiripple transitional Bessel-Chebyshev filters is derived. These filters have improved delay characteristics in comparison with Chebyshev phase characteristics and can provide more attenuation in the stopband than Butterworth filters. Design information in tabular form is given for filters up to 10th-order.<>     

A method for design of Mth-band filters

The objective of this paper is to present a theory, constraints, and a design method for nonlinear-phase halfband and Mth-band filters. Based on a time-domain property, the constraints and properties in the frequency domain are derived. They are the generalization of the well-known conditions for linear-phase Mth-band filters. Having found all necessary conditions, we present the design method based on an eigenfilter that minimizes the mean-squared errors. The design method is also extended to the design of nonlinear-phase Mth-band filters with properties of R-regularity, or equiripple stopband attenuation, or impulse responses that have complex coefficients. Design examples of various Mth-band filters with different properties are presented, discussed, and compared with the linear-phase case     

A new design for digital adaptive filters

The design and operation of a digital adaptive filter based on a modified Widrow-Hoff algorithm is described. It uses LSI components as main elements. This filter realization converges faster than other realizations reported hitherto because its weight vector is updated at every sampling instant.     

A design philosophy for microelectronic active-RC filters

A design philosophy for microelectronically realizable active-RC filters is presented and illustrated by means of microelectronic filter examples in the frequency range from approximately 75 Hz to about 110 kHz. The design is by simulation of low-sensitivity resistively terminated inductor-capacitor filters (LCR filters). Based on an analysis of the effect of nonideal components in the active-RC filters, functional adjustment methods are developed which lead in practice to near-ideal nominal response characteristics, in many cases better than those of practical LCR filters. By matching the design process to a carefully chosen well-established manufacturing technology, the cost of the microelectronic active-RC filters is attractively low. Many of these filters in microelectronic form are in production in the U.K.     

A novel approach for the design of pulse shaping filters

In this work, we propose a new class of pulses for PAM type digital signals. The pulses are designed based on minimization of a figure of merit that is the product of the Cramer-Rao bound of the timing jitter variance and the mean eye closure rate. The new pulses are seen to yield significantly better performances as compared to the classical ones.     

A method for accelerating the design of optimal linear-phase FIRdigital filters

A simple method is presented for reducing the execution time of the McClellan-Parks-Rabiner (1973) FIR (finite impulse response) digital filter design program on computers with a floating-point processor. It is found that 80% to 90% of the execution time of this program involves only four lines of the program code. By efficiently implementing these four lines of code in assembly language it is possible to significantly reduce the execution time. Examples of this method are given for personal computers based on both 8086-family and 68000-family microprocessors with a corresponding math coprocessor. It is found that for these computers the method reduces execution time by a factor of 1.6 to 1.9     

Method for design of allpass filters

A new method for allpass filter design is presented. The method leads to a solution for the phase that is equal to the desired phase for 2N+1 values of frequency (if N is the order of the allpass filter). These values can be chosen at will in the approximation interval. The resulting phase error therefore displays a ripple behaviour. The solutions obtained in this way could be used as an initial solution for an exchange algorithm in order to produce an equiripple solution     

Computational algorithm for the design of elliptic filters

A simple and fast algorithm, based on the simultaneous cheby?shev character of the passband and stopband characteristic, is presented for the computation of the transfer function of elliptic filters. The algorithm does not use elliptic functions; rather, a set of nonlinear equations is established and solved using Newton's method. Since useful initial approximations are easy to find, the solution requires only 2?4 iterations. The results are obtained directly in the transformed variable z and hence are immediately usable for computer-aided design.     

A design method of optical bandpass filters

A design method of optical bandpass filters which are composed of several resonators consisting of dielectric layers is discussed. The relation between the loaded Q of a resonator and the thickness of each layer is calculated by treating equivalently each layer as a segment of transmission line and represented on a chart. It becomes possible to design an arbitrary value of loaded Q by using the chart. Thus, an optical bandpass filter of required bandwidth and rejection characteristic can be designed by finding out the optimum thickness of each layer of the resonator which is the component of the filter     

A design of linear-phased IIR Nyquist filters

This paper discusses a new method of designing linear-phased IIR Nyquist filters with zero intersymbol interference. The filters designed by this method possess linear-phase characteristics and are lower in order than other Nyquist filters designed by existing methods. Expressions are derived for zero-phased IIR Nyquist filters and efficient design methods are examined for them. The opted design method is based on an iteration process, and in each iteration step a modified version of the Remez exchange algorithm is used. In addition, the implementation of the designed zero-phased IIR filters is considered. Finally, the proposed design method is demonstrated through various design examples     

A simple and effective method for microstrip dual-band filters design

A new type of novel low loss dual-band microstrip filters using folded open-loop ring resonators (OLRRs) is presented in this letter. Both magnetic and electric coupling structures are implemented to provide high performance passband response. The first passband and second passband of the designed dual-band filter can be easily and accurately shifted to a desired frequency band by adjusting the physical dimensions of OLRRs. Finally, the 2.4-GHz/5.7-GHz and 2.4-GHz/5.2-GHz dual-band filters are illustrated and measured in this letter.     

A fast perturbation method for the design of linear phase fir digital filters of finite wordlength using single-frequency filters

In this paper a fast perturbation algorithm for the design of linear phase FIR digital filters of finite wordlength is presented. The original set of filter coefficients are obtained using the Parks-McClellan algorithm, then a small perturbation is given to these sets of coefficients. The peak deviations corresponding to the rounded set of coefficients obtained from the original and the perturbed sets are compared and the set of coefficients with the lower value of peak deviation is stored as the best set of coefficients. A further perturbation is given to the infinite precision coefficents and these are rounded to the required wordlength. Comparison is made between these rounded sets and the present best set with respect to peak deviation and the better set is stored as the best set of coefficients. This process is repeated for a finite number of times or until the peak deviation is sufficiently low. To obtain the compensating filter coefficients single-frequency filters are used. Mathematical justification for the single-frequency design is given. Important results for a large number of design examples are presented to illustrate the speed and effectiveness of the algorithm.     

A new method for the design of IIR filters with flat magnitude response

This paper presents a new direct design of infinite-impulse response (IIR) filters with a flat magnitude response in both passband and stopband (Butterworth filters). The design specifications are passband and stopband frequencies and passband droop and stopband attenuation. The approach is based on an allpass filter with flatness at frequency points /spl omega/=0 and /spl omega/=/spl pi/. Depending on the parity of the IIR filter order, the allpass filter is either real or complex. However, in both cases, the resulting IIR filter is real.     

A universal building block for advanced modular design of microwave filters

A universal building block for modular design of microwave filters is introduced. The second order block contains two resonators which are not coupled to each other. By adjusting the strengths and signs of its coupling coefficients, the block can be used to design bandpass, bandstop and linear-phase filters. For bandpass filters, Chebychev as well as symmetric and asymmetric pseudo-elliptic responses with one or two finite transmission zeros can be designed. For linear-phase filters, two finite transmission zeros can placed practically anywhere in the complex plane as long as the realizability condition is met. Bandstop filters with no finite reflection zeros as well as symmetric and asymmetric pseudo-elliptic responses with one or two finite reflection zeros can be achieved by the same building block. The block is so flexible it can even generate bandstop responses with complex finite reflection zeros for group delay control. Higher order filters are designed modularly by cascading the appropriate number of building blocks. Coupling matrices of a number of cases are presented to demonstrate the flexibility and the universality of the building block.     

Mathematical methods for the design of color scanning filters

The problem of the design of color scanning filters is addressed in this paper. The problem is posed within the framework of the vector space approach to color systems. The measure of the goodness of a set of color scanning filters presented in earlier work is used as an optimization criterion to design color scanning filters modeled in terms of known, smooth, nonnegative functions. The best filters are then trimmed using the gradient of the mean square DeltaE(ab) error to obtain filters with a lower value of perceptual error. The results obtained demonstrate the utility of the method.     

Scattering matrix approach for the design of microwave filters

A synthesis procedure, based on a distributed parameter model, for the design of microwave filters is presented in this paper. The frequency response of the filter is described in terms of the characteristic polynomial T₂₁=S₁₁/S₂₁ where S₁₁ and S₂₁ are the scattering parameters of the filter. Starting from the desired polynomial T₂₁, the design scheme directly yields the scattering parameters of the various junctions, which can be realized by any kind of discontinuity. The capability of synthesizing an arbitrary frequency response allows one to introduce the concept of a “predistorted” characteristic polynomial in order to compensate for the degradations caused by multimodal interactions, frequency dispersion, etc. Comparison with measured data of a Chebyshev-like eight-pole E-plane filter confirms the validity of the method also in the presence of losses