Time-invariant Digital Filters Research Articles

A Unifying Framework for Finite Wordlength Realizations

A general framework for the analysis of the finite wordlength (FWL) effects of linear time-invariant digital filter implementations is proposed. By means of a special implicit system description, all realization forms can be described. An algebraic characterization of the equivalent classes is provided, which enables a search for realizations that minimize the FWL effects to be made. Two suitable FWL coefficient sensitivity measures are proposed for use within the framework, these being a transfer function sensitivity measure and a pole sensitivity measure. An illustrative example is presented.

Digital techniques for real-time pulse shaping in radiation measurements

Recursive algorithms for real-time digital pulse shaping in pulse height measurements have been developed. The differentiated signal from the preamplifier (exponential pulse) is amplified and then digitized. Digital data are deconvolved so that the response of the high-pass network is eliminated. The deconvolved pulse is processed by a time-invariant digital filter which allows trapezoidal/triangular or cusp-like shapes to be synthesized. A prototype of a digital trapezoidal processor was built which is capable of sampling and processing digital data in real time at clock rates up to 50 MHz.

Theory and applications of all-digital N-path filters

The all-digital N -path filter structure for the processing of discrete-time signals is introduced. The structure is made of N parallel paths having identical time-invariant digital filters. The filters are connected to a common input signal path through input modulators, and a common output signal path through output modulators. The modulators produce identical periodic sequences but are staggered in phase from filter to filter. A detailed time-domain and frequency-domain analysis of the N -path filter is provided. It is shown that for certain bandlimited modulating sequences, or by appropriately bandlimiting the input and output signals, the overall time-varying structure can be made to appear as a timeinvariant network. This approach leads to filters with adjustable characteristics, and it is shown that by time-sharing the time-invariant digital filter path N times, it is possible to design filters with complex characteristics quite economically. A number of useful modulating functions are described, and some possible applications are discussed.

VLSI arrays for digital signal processing:Part I-A model identification approach to digital filter realizations

A study of VLSI arrays that implement single-input singleoutput linear time-invariant digital filters is initiated in this paper. The arrays are restricted to be comprised of several similar processing elements in a linear configuration with only nearest neighbor links. The requirement of pipelineability in the resulting circuits is also imposed. A general framework is developed for the design of such arrays when each processing element is assumed to have a certain model with a single state variable. Several existing canonical form realizations are shown to be obtainable as special cases of the array configurations developed in this paper.

A general realization scheme of periodically time-varying digital filters

A new method is introduced for the exact decomposition of a linear <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</tex> th-order periodically time-varying digital filter into a set of independent, linear time-invariant, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</tex> th-order digital filters, each one of which is a single-input, multiple-output system plus a set of parallel blocks of multiply-in, add-out type of operations. It is shown that the adopted vector decomposition approach yields a general realization scheme that exhibits high parallelism as well as great regularity. The application of the vector decomposition method to the realization of linear time-invariant digital filters is also examined as a special case of the general one.

Comments on "Active Simulation of Grounded Inductors using a Single Current Conveyor

A new transform that is useful for the analysis of linear, time-varying (shift-variant) digital filters containing the gener- alized delay elements, as defined in earlier pages, constant multipliers and adders is proposed and some properties of the transform are derived. The algorithm based on Theorem 1 for computing the response of such filters is very simple. This algorithm can also be used to synthesize time-varying digital filters from given input-output relationship by reducing the problem to that of synthesizing time-invariant digital filters.