Butterworth filter

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

A Reconfigurable Micromachined Switching Filter Using Periodic Structures

Abstract: In this paper, a reconfigurable filter using micromachined switches is designed, fabricated, and experimented. An equivalent-circuit model is derived for the reconfigurable cell structure. Extracted parameters show the characteristics of both bandpass and bandstop filters, which can be accurately analyzed using circuit analysis. Coplanar waveguide transmission lines for the reconfigurable filter are also analyzed. The bandpass filter is formed by cascading the unit cell structure. This bandpass filter can be switched to bandstop filter using the micromachined switches and p-i-n diode. Dispersion characteristics are obtained to investigate the electromagnetic wave behavior within the unit cell using Floquet's theorem. Measurement results with micromachined switches show that insertion loss is 1.55 dB for the bandpass filter whereas band rejection level is >20 dB and the insertion loss in the passband is 1.2 dB for the bandstop filter. With the p-i-n diode, the insertion loss is 2.1 dB and the 3-dB bandwidth is 5.2 GHz for the bandpass filter, the 20-dB rejection bandwidth is 5.3 GHz, and the insertion loss in the passband is 1.6 dB for the bandstop filter.

Low-noise tunable filter design by means of active components

Abstract: A low-noise tunable filter with high dynamic range and minimum power consumption is presented and addressed with circuit details. It is based on an active solution simulating an inductive behaviour that allows improving the filter quality factor without affecting the noise performance. The low-order bandpass filter is realised with minimum number of components and it is suitable to be integrated in integrated circuit or used in hybrid transceiver and modern reconfigurable radio systems. A prototype board with discrete components has been fabricated and tested with good results.

Multi-frequency digital low pass filter for magnetic resonance imaging

Abstract: A digital lowpass filter design for filtering nuclear magnetic resonance (NMR) signals in a magnetic resonance imaging (MRI) system supports multiple frequencies and is highly configurable without sacrificing speed and performance. The first FIR filter stage of a synchronized multirate digital filter is selected from a database of filter coefficient/parameter sets which are loaded at start time and used in place. Second (and later) FIR filter stages are fixed in the example. A large number of different filter frequencies can be selected rapidly without changing the parameterized filter program reducing the amount of time to start up the MRI system and allowing "on-the-fly" filter changes in real-time between echoes and/or A/D samples. For example, filter preselection by the host can be performed in less than 100 μs, and, one of several lowpass filters can be selected by the sequencer "on-the-fly" with a latency of less than 10 μs.

Filter set for frequency analysis

Abstract: A system and method are disclosed for analyzing an input signal (100) into a plurality of frequency components. In one embodiment, the input signal (100) is processed with a first set of low pass filters (102-132) to derive a first set of frequency components wherein the first set of low pass filters (102-132) are arranged serially in a chain having a first low pass filter (102) and a last low pass filter (132), the output of each low pass filter being fed to the next low pass filter in the chain until the last low pass filter (132). The output of the last low pass filter (132) is downsampled (140) to produce a downsampled signal. The downsampled signal is processed with a second set of low pass filters (142-172) to derive a second set of frequency components.

Dual-bandpass filters with serial configuration using LTCC technology

Abstract: A dual-bandpass filter that utilizes a serial configuration of the inductive coupled-line (ICL) filter and the capacitive coupled-line (CCL) filter is investigated in this study. Numerical analysis is presented for the difference between the ICL and CCL filters. The dual-bandpass filter has a similar behavior to the individual single-band filter around the corresponding passband. An extra transmission zero can be generated between the two passbands of the dual-bandpass filter in that the ICL and CCL filters exhibit an out-of-phase response. Four architectures of dual-bandpass filters are proposed for the 2.4/5-GHz systems. Two of them are demonstrated by the low-temperature co-fired ceramic multilayer technology. Measurements results agree quite well with the simulation ones