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1

Design of a Fractional Order Low-pass Filter Using a Diﬀerential Voltage Current Conveyor

Krishna Battula Tirumala, Janarthanan Midhunchakkaravathy

Journal of Telecommunications and Information Technology

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2023

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nr 2

17--21

EN

In this paper, an active implementation of a diﬀerential voltage current conveyor (DVCC) based on a low-pass ﬁlter operating in the fractional order domain is presented. The transfer function for a fractional order system is dependent on the rational approximation of sα. Diﬀerent methods used for calculating the rational approximation, including Carlson, Elkhazalil, and curve ﬁtting, are evaluated here. Finally, to validate the theoretical results, a fractional order Butterworth ﬁlter is simulated in the Pspice environment using the 0.5 micrometer CMOS technology with an R-C network-based fractional order capacitor. Additionally, using the Monte Carlo analysis, the impact of current and voltage faults on DVCC response is investigated. It has been inferred that realization with a wider bandwidth is possible.

2

FIR Filter Design Using Distributed Maximal Flatness Method

Blok M.

International Journal of Electronics and Telecommunications

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2013

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Vol. 59, No. 1

59-66

EN

In the paper a novel method for filter design based on the distributed maximal flatness method is presented. The proposed approach is based on the method used to design the most common FIR fractional delay filter - the maximally flat filter. The MF filter demonstrates excellent performance but only in a relatively narrow frequency range around zero frequency but its magnitude response is no greater than one. This "passiveness" is the reason why despite of its narrow band of accurate approximation, the maximally flat filter is widely used in applications in which the adjustable delay is required in feedback loop. In the proposed method the maximal flatness conditions forced in standard approach at zero frequency are spread over the desired band of interest. In the result FIR filters are designed with width of the approximation band adjusted according to needs of the designer. Moreover a weighting function can be applied to the error function allowing for designs differing in error characteristics. Apart from the design of fractional delay filters the method is presented on the example of differentiator, raised cosine and square root raised cosine FIR filters. Additionally, the proposed method can be readily adapted for variable fractional delay filter design regardless of the filter type.

3

Realizacja układu różniczkującego jako obwodu wewnętrznie nieliniowego

Topór-Kamiński L.

Zeszyty Naukowe. Elektryka / Politechnika Śląska

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2004

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z. 190

133-145

PL

Przestawiono teoretyczną koncepcję budowy układu różniczkującego z zastosowaniem jedynie bloków o nieliniowych funkcjach przetwarzania, należącego do obwodów typu zewnętrznie liniowych, wewnętrznie nieliniowych (ZLWN). Pokazano ogólny model teoretyczny dla funkcji potęgowej oraz jego wersje dla różnych potęg wykładnika. Omówiono także postacie układu różniczkującego o logarytmicznych, wykładniczych oraz modułowych funkcjach przetwarzania. Pokazano przykłady ich realizacji praktycznych z zastosowaniem dwójników nieliniowych, wzmacniaczy jednostkowych i konwejerów prądowych. Przedstawiono otrzymane symulacyjnie przebiegi czasowe sygnałów zewnętrznych i wewnętrznych przykładowego układu różniczkującego typu ZLWN.

EN

Theoretical conception of realisation of differentiator using only nonlinear blocks of the externally linear internally nonlinear (ELIN) type has been described in the paper. The general theoretical model for power function and its two versions for different power values have been presented. Differentiators of logarithm, exponential and absolute value transmittance functions have been also discussed. The examples of their practical realisation with the use of nonlinear one- ports, voltage followers and current conveyors have been presented. The waveforms of external and internal signals of the exemplary ELIN type differentiator obtained from simulations have been shown.