Showing papers on "Prototype filter published in 1979"
01 Jan 1979
TL;DR: In this paper, the basic operation of switched-capacitor filters is reviewed, followed by a discussion of the properties of the various circuit building blocks in MOS technology, and a summary of several filter organizations which appear to be well suited to switch-capACitor implementation is presented.
Abstract: In the past several years, much progress has been made in bringing the economies of integrated-circuit technology to bear on the realization of voiceband frequency selective filters. This paper will review one approach to this problem, the use of switched-capacitor techniques. The paper emphasizes the practical aspects of switched-capacitor filter design under the constraints imposed by MOS integrated-circuit technology. The basic operation of switched-capacitor filters is reviewed, followed by a discussion of the properties of the various circuit building blocks in MOS technology. Finally, a summary of several filter organizations which appear to be well suited to switched-capacitor implementation is presented.
238 citations
TL;DR: In this article, a step-by-step design procedure for microstrip tapped-line filters, accompanied by appropriate design curves, is presented. And a new hairpin-line filter using tapping is introduced.
Abstract: The subject of this article is a step-by-step design procedure for microstrip tapped-line filters, accompanied by appropriate design curves. In addition to microstrip tapped-line interdigital filters, a new hairpin-line filter using tapping is introduced. The equation to equation the singly loaded Q for hairpin resonators produced by tapping is derived. Experimental data is presented for filters over 20-percent bandwidth.
223 citations
TL;DR: In this paper, sufficient conditions are derived for a second-order statespace digital filter with L 2 scaling to be optimal with respect to output roundoff noise; and from these, a simple synthesis procedure is developed.
Abstract: Sufficient conditions are derived for a second-order statespace digital filter with L_2 scaling to be optimal with respect to output roundoff noise; and from these, a simple synthesis procedure is developed. Parallel-form designs produced by this method are equivalent to the block-optimal designs of Mullis and Roberts. The corresponding cascadeform designs are not equivalent, but they are shown, by example, to be quite close in performance. It is also shown that the coefficient sensitivities of this structure are closely related to its noise performance. Hence, the optimal design has low-coefficient sensitivity properties, and any other low-sensitivity design is a good candidate for near-optimal noise performance. The uniform-grid structure of Rader and Gold is an interesting and useful case in point.
158 citations
TL;DR: The filter is designed so that binary changes in the sampling frequency provide new sets of center frequencies which smoothly continue the logarithmic progression, and the accuracy and reproducibility inherent in the switched capacitor approach are retained.
Abstract: Techniques are presented for the design of a second-order switched capacitor filter which has its frequency response parameters programmed by the application of digital control signals. Two different types of weighted capacitor arrays are used to achieve programmability in the center frequency, peak gain, and selectivity. Experimental results are given for an integrated NMOS version with eight logarithmically-spaced center frequencies programmed by a 3 bit digital word, and 64 Q and gain values programmed by two 6 bit words. The filter is designed so that binary changes in the sampling frequency provide new sets of center frequencies which smoothly continue the logarithmic progression. Since the response depends on monolithic MOS capacitor ratios, the accuracy and reproducibility inherent in the switched capacitor approach are retained.
76 citations
TL;DR: The direct form switched-capacitor offers some useful advantages in comparison to the switched-Capacitor integrator approach, including the rejection of MOS amplifier noise and power supply noise below one-half the sampling rate, less silicon area especially when implementing high Q poles, and potential for multiplexing two or more filters.
Abstract: A new technique enabling the integration of audio frequency filters using standard MOS technology is described. This approach uses ratioed MOS capacitors, MOS amplifiers and switches to realize precision multiplication, summation, and delay functions. With these elements an analog sampled-data direct-form recursive filter, having the general biquadratic transfer function, was integrated in MNOS technology. This filter had a Q=19/spl plusmn/1 without external trimming and it could be electrically programmed into low-pass, bandpass, and high-pass responses. This biquadratic section can be used as a building block for higher order filters. The direct form switched-capacitor offers some useful advantages in comparison to the switched-capacitor integrator approach. These are the rejection of MOS amplifier noise and power supply noise below one-half the sampling rate, less silicon area especially when implementing high Q poles, and potential for multiplexing two or more filters.
75 citations
01 Dec 1979
TL;DR: A fully integrated DTMF receiver has been fabricated on a single CMOS chip requiring only three external passive components and combines precision filters, zero crossing detectors and amplitude detectors with digital logic.
Abstract: A fully integrated DTMF receiver has been fabricated on a single CMOS chip requiring only three external passive components. The circuit combines precision filters, zero crossing detectors and amplitude detectors with digital logic. Switched capacitor techniques are used to implement high-pass, bandpass, and bandstop filters. The receiver architecture and circuit implementation are described.
65 citations
TL;DR: In this article, a new class of recursive digital filters for sampling rate reduction is discussed, which brings together the advantages of finite-duration impulse response (FIR) and elliptic designs by having only powers of zDin the denominator (D is the decimation ratio).
Abstract: A new class of recursive digital filters for sampling rate reduction is discussed. These filters present equiripple behavior in the magnitude response, with all their zeros located on the unit circle. These new filters bring together, to some extent, the advantages of finite-duration impulse response (FIR) and elliptic designs by having only powers of zDin the denominator (D is the decimation ratio). Only every D th output has to be computed, as in the FIR case; while some feedback terms, as in the elliptic case, are also present. The design and some optimality properties of these filters are discussed. Some characteristics of filters with only powers of zDin the denominator, such as pole-zero location, group delay, and coefficient sensitivity are discussed and compared with elliptic designs. It is shown how these new filters require significantly fewer multiplications per second than equivalent FIR and elliptic designs.
64 citations
01 Dec 1979
TL;DR: A closed form expression, for the single complex weight in the frequency domain adaptive filter, is presented which allows significant statistical analysis to be performed.
Abstract: The purpose of this note is to demonstrate significant analytical simplifications for studying the behavior of adaptive filtering in the frequency domain as opposed to studying the behavior of adaptive filtering in the time domain. A closed form expression, for the single complex weight in the frequency domain adaptive filter, is presented which allows significant statistical analysis to be performed. The mean-square error of the filter is evaluated as a function of the algorithm step size and the signal and noise powers.
63 citations
Patent•
05 Jun 1979TL;DR: In this article, a Lyot-type birefringent filter was proposed to achieve analytically useful levels of resolution and stray-light ratios for costs that are competitive with prism and grating monochromators.
Abstract: Moderately narrow band, tunable, birefringent filters are disclosed using zero-twist liquid crystal cells as variable retarders in a Lyot-type birefringent filter. These filters can achieve analytically useful levels of resolution and stray-light ratios for costs that are competitive with prism and grating monochromators. These birefringent filters can be tuned and/or rendered opaque by the application of a suitable voltage to the cells. Thus, a variety of different optical instruments can be constructed with no moving parts. Power requirements are negligible. A useful filter can be designed to occupy a volume less than one cubic inch. These properties render such a filter ideally suited to microprocessor control.
TL;DR: In this article, a new class of interpolators characterized by the property that the mean power of their error sequence, as a function of frequency, approximates zero in the Chebyshev sense is presented.
Abstract: The paper presents a new class of interpolators characterized by the property that the mean power of their error sequence, as a function of frequency, approximates zero in the Chebyshev sense. The design method, which is based on some observation and newly found general properties, will be described in some detail. An example shows the special properties of these interpolators in comparison with former results. Measurements done with a practical implementation are presented as well. A design chart for these filters is provided.
TL;DR: In this article, a systematic design procedure for the output filter of a single-phase uninterruptible power supply (UPS) system is developed, and four different output filter configurations are compared for sinusoidal pulsewidth and single-pulse modulated inverter output voltage.
Abstract: A systematic design procedure for the output filter of a singlephase uninterruptible power supply (UPS) system is developed. The basic specifications for the UPS system are first established. Four different output filter configurations are then analyzed and compared for sinusoidal pulsewidth and single-pulse modulated inverter output (i.e., filter input) voltage. On the basis of the above comparison, ``optimum'' filters are selected for both modulation techniques. Using a minimization function for filter cost and size, a set of filter design parameters corresponding to each type of modulation are obtained on the per unit basis. The theoretical results are verified on an experimental breadboard utilizing a current commutated thyristor inverter. Finally, the overall filter design procedure is outlined and a design example is presented.
TL;DR: In this article, the authors present a systematic design of digital filters that contain poles and zeros, which are then used to generate consistent unit-pulse and covariance sequences for use in the Mullis-Roberts algorithm.
Abstract: Procedures are presented for the systematic design of digital filters that contain poles and zeros. The procedures are simple, fast, and effective. All of the important algorithms are of the Levinson-type. The first key idea in the paper is that one may begin a design by posing a linear prediction problem for a stochastic sequence. The second is that a high-order "whitening" filter may be constructed for this sequence and "inverted" to yield a high-order all-pole filter whose spectrum approximates the spectrum of the stochastic sequence. The third key idea is that the all-pole filter may be used to generate consistent unit-pulse and covariance sequences for use in the Mullis-Roberts algorithm. This algorithm is then used to obtain a low-order digital filter, with poles and zeros, that approximates the high-order all-pole filter. The results demonstrate that the Mullis-Roberts algorithm, together with the design philosophy of this paper, may be used with profit to reduce filter or stochastic model complexity and to design spectrum-matching digital filters.
TL;DR: In this article, the authors proposed a method for the frequency domain design of linear two-dimensional analogue and digital filters with guaranteed stability. The technique used is based on the result that the numerator and the denominator of the input immittance of a two-variable network (which is passive and lossy) are strictly Hurwitz polynomials.
Abstract: A method is proposed for the frequency domain design of linear two-dimensional analogue and digital filters with guaranteed stability. The technique used is based on the result that the numerator and the denominator of the input immittance of a two-variable network (which is passive and lossy) are strictly Hurwitz polynomials. One of these strictly Hurwitz polynomials is assigned to the denominator of a two-variable analogue transfer function and the network elements are then used as the variables of optimization thereby guaranteeing the stability of the analogue transfer function. The transfer function of the corresponding two-dimensional discrete (digital) filter is obtained from the analogue transfer function by the bilinear transformation. Examples illustrating the versatility of the technique in designing 2D digital filters of arbitrary order approximating a given magnitude and group delay response are presented. These filters are used to process a simple binary image. The results obtained demonstrate the importance of linear phase in image processing applications.
The method presented here can be extended to the design of stable m-dimensional analogue and digital filters.
TL;DR: In this paper, the application of linear programming to the design of FIR digital filters with constraints on the derivative of the frequency response is described and numerical considerations in the implementation are discussed.
Abstract: The application of linear programming to the design of FIR digital filters with constraints on the derivative of the frequency response is described. Numerical considerations in the implementation are discussed and a program is given with examples for the design of filters with optional monotone response in passbands. The method provides the user with an additional degree of flexibility over the Remez exchange algorithm.
01 Jan 1979
TL;DR: In this article, the authors describe the operational features and performance of an integrated-circuit programmable sampled-analog data filter in transversal form using CCD/MOST technology.
Abstract: This paper describes the operational features and performance of an integrated-circuit programmable sampled-analog data filter in transversal form using CCD/MOST technology. Reasons behind the particular choice of filter architecture for a prototype realization and its comparison with other reported designs in this technology are discussed, with particular emphasis placed on a novel MOST multiplier array implementation. The performance characteristics of a prototype 64-point filter design based on this approach is detailed in the context of frequency- and matched-filtering, and a module of 256 points using four cascaded filters is also described. Techniques for optimizing the inherent performance limits of these filter types under microprocessor control are suggested, via the iterative adaption of the filter impulse response, and results are given to show the improvement obtained. Finally, the potential of this miniature integrated-circuit filter for sonar type applications is briefly discussed.
TL;DR: The first and second-order forms of a transformation for implementing a variable-cutoff linear-phase FIR filter are investigated in this paper, where correct constraints have been placed on the variable parameter A_0 ; it is pointed out that the cutoff frequency increases, while the cutoff slope decreases, monotonically with increasing A_v; A 0 = 0 corresponds to the prototype filter.
Abstract: The first- and second-order forms of a transformation for implementing a variable-cutoff linear-phase FIR filter are investigated. In the first-order case, correct constraints have been placed on the variable parameter A_0 ; it is pointed out that the cutoff frequency increases, while the cutoff slope decreases, monotonically with increasing A_v; A_0 = 0 corresponds to the prototype filter. The second-order transformation is shown to overcome these drawbacks without increasing the computational load or the number of variable parameters.
TL;DR: It is shown that the phase distortion introduced by the filter is zero and the application of the filter to smoother EP records is illustrated.
TL;DR: In this paper, a tunable, narrow-band thin-film filter consisting of two uniform grating filter sections separated by a phase shift section is proposed, and theoretically predicted performance of these new components is verified experimentally.
Abstract: A tunable, narrow-band thin-film filter consisting of two uniform grating filter sections separated by a phase-shift section is proposed, and the theoretically predicted performance of these new components is verified experimentally. A straightforward method of calculating the reflection spectrum of these structures is also presented; the technique is particularly well suited to accounting for the effects of parasitics in practical structures. Finally, a qualitative model useful for intuitive analysis of these filters and their spectra is described.
TL;DR: In this paper, a general characterization of second-order active-RC filters employing one, two, and three operational amplifiers is given, and it is shown that the desired poles can be rendered insensitive to first and second order changes in the time constants of the amplifiers.
Abstract: A general characterization of second-order active-RC filters employing one, two, and three operational amplifiers is given. When certain conditions are met, it is shown that the desired poles can be rendered insensitive to first- and second-order changes in the time constants of the operational amplifiers. Several novel circuits possessing this zero pole-sensitivity property, as well as zero \omega_0 and Q sensitivity properties, are presented and discussed. Experimental verification of the results and comparisons to other popular second-order active-RC realizations bear out the significantly superior performance of these filters.
TL;DR: An analytic design procedure for a realizable filter that meets a relatively large impulse response at t and near-zero responses at t = t_M + k ( k = any integer) and also optimizes other frequency and time domain criteria is given.
Abstract: A common requirement in the design of multilevel data transmission filters is to provide a relatively large impulse response at t= t_M and near-zero responses at t = t_M + k ( k = any integer), in order to minimize intersymbol interference. This paper gives an analytic design procedure for a realizable filter that meets this requirement in an optimal manner and also optimizes other frequency and time domain criteria. The results are then extended to handle nonimpulsive inputs (which includes nonideal channels).
TL;DR: In this paper, a bilinear frequency transformation is used to synthesize low-pass-prototype networks for narrow-bandpass filters, which allows the use of the constant reactance elements and results in a lowpass frequency response that may not be symmetric about zero frequency.
Abstract: A bilinear frequency transformation can be used to synthesize low-pass-prototype networks for narrow-bandpass filters. The lowpass prototype is based on the narrow-band approximation of circuit theory, which allows the use of the constant reactance elements and results in a lowpass frequency response that may not be symmetric about zero frequency. With an appropriate transformed variable, the numerical accuracy of the synthesis procedure is enhanced and the approximation problem is simplified. This technique is applicable to a broad class of filters using microwave cavity, mechanical, crystal or lumped-element resonators. Synthesis on an insertion loss basis is described for lossless doubly terminated filters, with an example of a coupled-resonator filter realization.
TL;DR: A simple estimate of the order of optimum FIR bandpass filters is presented and the accuracy of the estimate is demonstrated.
Abstract: The computer program of [1] for the design of optimal FIR filters requires, as an input, the order of the filter to be designed. A reliable order estimate for the case of low-pass filters is known [2]. In this paper, we present a simple estimate of the order of optimum FIR bandpass filters. The accuracy of the estimate is demonstrated.
TL;DR: In this article, a new approach to roughness filtering is described using digital filters designed and simulated in a general purpose computer, which is used to process the digitized surface profiles and the performance is compared with that of available analogue filters.
TL;DR: In this article, the authors present a synthesis procedure for a class of two-dimensional recursive filters based on the minimization of the mean square error between the synthesized filter and a given prototype.
Abstract: This paper presents a synthesis procedure for a class of two-dimensional recursive filters. The test of stability for such filters is easy. The design method is based upon minimization of the mean-square error between the synthesized filter and a given prototype.
01 Jan 1979
TL;DR: This letter works out a transformation for obtaining a linear phase variable cut-off low-pass digital filter for linear phase bandpass digital filters with variable bandwidth and center frequency.
Abstract: A transformation for obtaining a linear phase variable cut-off low-pass digital filter has been recently described in the literature [1]. In this letter, this transformation is worked out for the case of linear phase bandpass digital filters with variable bandwidth and center frequency.
01 Oct 1979
TL;DR: A simple and computationally fast scan-ordered one-dimensional Kalman filter is derived, which is then provided with additional structural information about the edges in the noisy image and behaves like the original noise-smoothing Kalman Filter if no edges are present but has a greatly improved step response.
Abstract: Recursive Kalman filters are often used for noise reduction in image data. These linear filters are based on the second-order statistics of image and noise. The noise is effectively reduced by the filtering operation, but the edges in the image are blurred and image contrast is reduced as well. These effects decrease the subjective quality of the image. A simple and computationally fast scan-ordered one-dimensional Kalman filter is derived, which is then provided with additional structural information about the edges in the noisy image. This filter behaves like the original noise-smoothing Kalman filter if no edges are present but has a greatly improved step response. In this way the edge-blurring phenomenon is effectively reduced. Results of several experiments are presented to demonstrate the feasibility of our approach.
TL;DR: In this paper, a computer-aided design procedure of microstrip filters involving junctions and discontinuities is investigated, which leads to an accurate fast numerical computation of the microstrip filter properties.
Abstract: A computer-aided design procedure of microstrip filters involving junctions and discontinuities is investigated. The analysis of microstrip filters is described in detail considering disperion, loss, and the frequency dependent properties of the microstrip discontinuities. It is found that the described analysis procedure leads to an accurate fast numerical computation of the microstrip filter properties. The theoretical results for some filter structures are compared with measurements, and theory and experiment are found to correspond closely.