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Butterworth filter

About: Butterworth filter is a research topic. Over the lifetime, 6187 publications have been published within this topic receiving 69070 citations.


Papers
More filters
Journal ArticleDOI
01 Apr 2011
TL;DR: An improved closed form method for designing cosine modulated filter banks with prescribed stopband attenuation and channel overlap based on optimum passband frequency is presented, which is calculated using empirical formulas instead of using time consuming single or multivariable optimization.
Abstract: This paper presents an improved closed form method for designing cosine modulated filter banks with prescribed stopband attenuation and channel overlap. The proposed method is based on optimum passband frequency, which is calculated using empirical formulas instead of using time consuming single or multivariable optimization. Different window functions are employed to design the prototype filter with the novelty of exploiting spline functions in the transition region of the ideal filter. Several design examples are included to show the increased efficiency of the proposed method over other exiting methods in terms of computation time, amplitude distortion (e"a"m) and aliasing distortion (e"a). An application of the proposed method is considered in the area of subband coding of the ECG and speech signals.

27 citations

Journal ArticleDOI
TL;DR: In this paper, an analytical expression for the output power spectral density is derived for a class of oscillators, which can be modeled by a positive feedback system with a frequency-selective Mth-order filter, an ideal comparator, and a white noise source.
Abstract: This paper presents noise analysis of a class of oscillators, which can be modeled by a positive feedback system with a frequency-selective Mth-order filter, an ideal comparator, and a white noise source. An explicit analytical expression for the output power spectral density is derived. A simplified expression is obtained for a special case when the Mth-order filter is replaced by a second-order bandpass filter. The general expression is shown to reduce to a well-known result if a high and-factor filter is further assumed. Theoretical results presented here are verified by experiment.

27 citations

Patent
24 Sep 1999
TL;DR: In this paper, a method and system for tuning a tunable bandpass filter includes a band-pass filter having a passband which is dependant on the value of a tuning signal.
Abstract: A method and system for tuning a tunable bandpass filter includes a bandpass filter having a passband which is dependant on the value of a tuning signal. A data signal having a dominant frequency component is applied to the filter and the power of the signal passed by the filter is determined. The tuning signal is adjusted until the passed power is maximized, indicating that the filter is tuned to the dominant frequency. The tuning signal can then be applied to other tunable circuits, including an oscillator having an output used as a clock signal to extract data from the data signal applied to the filter.

27 citations

Journal ArticleDOI
TL;DR: In this paper, a fractal-based complementary split-ring resonator (CSRR) has been introduced as a defected ground structure in the ground plane of a dual-mode microstrip bandpass filter to produce a new compact filter with dual-band response.
Abstract: In this paper, a fractal-based complementary split-ring resonator (CSRR) has been introduced as a defected ground structure (DGS) in the ground plane of a dual-mode microstrip bandpass filter to produce a new compact filter with dual-band response. The conventional double square ring resonator structure is modified such that its inner ring is made with a fractal shape instead of a square. Measured and simulation results show that the resulting filter offers a dual passband response; the higher passband is attributed to the dual-mode microstrip ring structure, whereas the lower passband is as a result of the embedded CSRR DGS structure. In addition, the results show that the position of the lower passband could be varied, to a certain extent, without affecting the position of the higher passband by applying higher fractal iteration levels to the inner split ring. These features, together with the compact size the proposed filter offers, make it suitable for use in a wide variety of dual-band communication applications. Measured results, carried out on filter prototypes, have been found in agreement with those theoretically predicted.

27 citations

Proceedings ArticleDOI
20 Jun 2004
TL;DR: In this article, a fully-digital-controlled shunt hybrid active filter for damping of harmonic propagation in power distribution systems is presented, which is based on installation of a shunt pure active filter at the end of a feeder.
Abstract: This paper presents a fully-digital-controlled shunt hybrid filter for damping of harmonic propagation in power distribution systems. The harmonic propagation is caused by resonance between line inductances and power capacitors installed for power factor correction. A possible solution to damping out harmonic propagation is based on installation of a shunt pure active filter at the end of a feeder This paper proposes a shunt hybrid active filter characterized by series connection of a 7th tuned LC filter per phase and a small-rated three-phase active filter. Like the pure filter, the hybrid filter is connected to the end bus of a feeder. The capacitor of the LC filter imposes a high impedance to the fundamental frequency, so that the fundamental voltage appears across the capacitor. This unique feature allows us to directly connect the hybrid filter to the 6.6 kV power line without step-down transformers. Furthermore, the capacitor used in this hybrid filter is lighter, cheaper and smaller than the transformer used in the pure filter. Theoretical analysis, along with experimental results obtained from a 200-V, 20-kW laboratory system, verifies the viability and effectiveness of the proposed hybrid filter.

27 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202322
202282
202140
202059
201941
201864