Topic
Butterworth filter
About: Butterworth filter is a research topic. Over the lifetime, 6187 publications have been published within this topic receiving 69070 citations.
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Papers
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TL;DR: In this paper, the cutoff slope and minimum attenuation in the stopband are derived in terms of n, the number of pairs of zeros (m) and their locations, and the information required for design of finite zero filters is provided in the form of universal graphs.
Abstract: Maximally flat (MF) low-pass filters with multiple pairs of coincident or distinct imaginary axis zeros are investigated and compared with the all pole Butterworth filters. It is shown that for the same order n , finite zero filters provide much sharper cutoff than Butterworth filters, and that the cutoff slope increases with increasing number of zeros. Expressions for cutoff slope and minimum attenuation in the stopband are derived in terms of n , the number of pairs of zeros ( m ) and their locations. In the case of coincident multiple zeros, the stopband performance is found to be an optimum for a particular value of m . The information required for design of finite zero filters is provided in the form of universal graphs and use of these graphs is illustrated by a design example.
23 citations
TL;DR: In this article, a trisection stepped impedance resonators in microstrip medium were used for low-pass filter with wide-stop band region using trisector stepped impedance (TSEM) resonators.
Abstract: This paper reports the design of a compact low pass filter (LPF) with wide stop band region using trisection stepped impedance resonators in microstrip medium. Experimental results of a low pass filter designed at 1 GHz have been compared against the analytical and EM simulation results for the validation of the design. Results are satisfactorily matching each other. The maximum insertion of the measured filter is 0.2 dB and minimum return loss is 13.5 dB over the pass band. The stop band rejection is better than 20 dB from 1.5 GHz to 4.2 GHz and hence wide stop band performance is achieved. Overall size of the filter is 30 mm x 20 mm x 0.78 mm which is 0.1 lambda x 0.066 lambda. x 0.0026 lambda at 1 GHz. (C) 2011 Elsevier GmbH. All rights reserved.
23 citations
TL;DR: The performance of the series optimization is demonstrated to be superior to the optimization techniques used in previous literature in terms of roll-off error, 3 dB frequency error, PE, SE, phase error and speed.
Abstract: The design and realization of fractional-order low-pass Butterworth filter (FOLPBF) for order (1 + α), with 0 < α < 1, optimized using a speed enhanced series combination of two meta-heuristic algorithms, namely cuckoo search algorithm (CSA) and interior search algorithm (ISA), is presented in this paper. This method optimizes both the gain and phase for the FOLPBF with respect to the ideal second-order Butterworth filter. The improvement in CSA → ISA series algorithm is established over standalone optimization using CSA and ISA on the basis of gain error, roll-off error, 3 dB frequency error, magnitude error [including passband error (PE) and stopband error (SE)], phase error, and convergence rate. The performance of the series optimization is demonstrated to be superior to the optimization techniques used in previous literature in terms of roll-off error, 3 dB frequency error, PE, SE, phase error and speed. The transient responses achieved with CSA → ISA series optimization is compared with the ideal response using Simulink simulations.
23 citations
22 Feb 2013
TL;DR: The IIR digital notch filter method is used for industrial frequency interference filter and the algorithm deduced on the fixed-point DSP programming method and overflow handling problems made elaborate incisively in digital audio signal processing system has been applied.
Abstract: In this paper the AC power 50Hz power interference, we use IIR digital notch filter method for industrial frequency interference filter. From the design of IIR digital filter method proceed with, on the IIR digital notch filter simulation, the algorithm deduced, on the fixed-point DSP programming method and overflow handling problems made elaborate incisively, and in digital audio signal processing system has been applied.
23 citations
Patent•
30 Aug 2007TL;DR: In this paper, a digital tuning system for changing a cutoff frequency of an analog filter is described. But the filter is sequenced through a plurality of capacitance settings and an optimal capacitance for the R/C circuit is selected by comparing, to a pre-selected value, a difference between the responses of the filter to each tone, for each capacitance setting.
Abstract: A digital tuning system (250) for changing a cutoff frequency of an analog filter (132) includes digital synthesizers (292 and 294) for producing a two-tone calibration signal (196) applied to an input of the filter after a quality factor of the filter is increased The filter includes at least one R/C circuit with two resistors (304 and 306) for changing the quality factor and arrays (308 and 310) of capacitors for changing the cutoff frequency The amplitude of the magnitude responses (409 and 411 ) of the filter to each tone (405 and 407) is measured by a two discrete Fourier transform single-frequency bin power detection circuits 10 (253 and 254) while the filter is sequenced through a plurality of capacitance settings An optimal capacitance for the R/C circuit is selected by comparing, to a pre¬ selected value, a difference between the responses of the filter to each tone, for each capacitance setting.
23 citations