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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
TL;DR: By using a methodical approach, the stability problems and much of the time-consuming experimentation common to radio frequency (RF) oscillator design was avoided and the problems of mode hopping and oscillation at harmonics were avoided.
Abstract: This paper presents electronic techniques and a general methodology for the rapid design of two-port surface acoustic wave oscillators. By using a methodical approach, the stability problems and much of the time-consuming experimentation common to radio frequency (RF) oscillator design was avoided. Several oscillators in the range of 200 MHz to 1 GHz were designed using variations of the same basic circuit. Circuit designs included both two-port resonator and delay line SAW devices. The electronics were small in size ( 1.75 cm ×1.75 cm ) and inexpensive ( The first step of this systematic method was to identify a readily available RFIC amplifier that met the specifications of the oscillator. The specifications included amplifier gain, bandwidth and maximum input power. Choice of the proper amplifier allowed the same circuit to be used for several SAW oscillators spanning a large frequency range. Next a passive LC filter was designed to limit the open loop gain to a small frequency region around the SAW device’s fundamental frequency. This filter eliminates the problems of mode hopping and oscillation at harmonics. The S-parameters of the oscillator were then measured in an open-loop configuration to determine the phase shift requisite for the closed loop oscillation condition of 0° phase shift. To achieve stable oscillation, a passive LC phase-shifting filter was designed. Using the properties of Butterworth filters and a simple computer program, filters of exact phase shift were designed. The last step of design was the use of microstrip layout techniques to reduce wave reflections and susceptibility to electromagnetic interference.

36 citations

Proceedings ArticleDOI
28 Apr 1995
TL;DR: It is shown that the MDFT filter bank structure provides a cancellation of all odd alias spectra and it is demonstrated that even perfect reconstruction can be obtained by an appropriate filter design.
Abstract: The Modified DFT (MDFT) polyphase filter bank has been introduced. It has been shown that this filter bank is able to cancel adjacent channel alias spectra resulting in almost perfect reconstruction. Compared to cosine modulated filter banks, the MDFT filter bank offers advantages such as linear phase analysis and synthesis filters, complex valued signal processing with a different mapping into the subbands and low propagation delays. In this paper, it is shown that the MDFT filter bank structure provides a cancellation of all odd alias spectra. Furthermore, it is demonstrated that even perfect reconstruction can be obtained by an appropriate filter design.

36 citations

Patent
31 Jul 1997
TL;DR: In this article, a dual-band multilayer bandpass filter with a first filter unit and a second filter unit was proposed for filtering a first signal having a first frequency and filtering a second signal with a second frequency.
Abstract: A dual-band multilayer bandpass filter having a first filter unit (18) for filtering a first signal having a first frequency and a second filter unit (19) for filtering a second signal having a second frequency. First and second filter units are arranged in stacked ceramic layers. A first blocking element (20a, 20b; 25a, 25b; 25a', 25b'; 46a, 46b) is coupled to the first filter unit (18) for blocking the second signal from being applied to the first filter unit (18). A second blocking element (21a, 21b; 26a, 26b; 25c, 25d; 27a, 27b) is coupled to the second filter unit (19) for blocking the first signal from being applied to the second filter unit (19).

36 citations

Patent
16 Mar 2005
TL;DR: In this paper, the authors propose a high-frequency circuit for demultiplexing highfrequency signals of communication methods of different frequencies, which consists of a low-pass filter circuit between first and second ports and/or a high pass filter circuit provided between the first port and a forth port.
Abstract: A high-frequency circuit for demultiplexing high-frequency signals of communication methods of different frequencies. The high-frequency circuit comprises a lowpass filter circuit provided between first and second ports and/or a highpass filter circuit provided between the first port and a forth port and a matching circuit and a bandpass filter both provided between the first port and a third port. The lowpass filter circuit, the highpass filter circuit, and the matching circuit each have a capacitance element and inductance element. The bandpass filter circuit is composed of an SAW filter. The passband f1 of the lowpass filter circuit, the passband f2 of the bandpass filter circuit, and the passband f3 of the highpass filter are in a relation f1

36 citations

Journal ArticleDOI
TL;DR: A low-voltage low-power signal processing chip for electrocardiogram measurements has been designed and manufactured and is very suitable for portable applications such as heart rate detectors.
Abstract: A low-voltage low-power signal processing chip for electrocardiogram measurements has been designed and manufactured. The circuit includes a continuous time, offset-compensated preamplifier with an amplification of 40 dB, an eighth-order Butterworth switched-opamp switched-capacitor (SO-SC) filter with a passband of 8-30 Hz, a 32-kHz crystal oscillator, an SO-SC postamplifier, and a bias circuit. The whole circuit operates with supply voltages from 1.0 to 1.8 V and the measured average current consumption is only about 3 /spl mu/A. The circuit is therefore very suitable for portable applications such as heart rate detectors.

36 citations


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