Butterworth filter

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

A compact low-loss Ka-band filter using 3-dimensional micromachined integrated coax

Abstract: This paper presents a novel low-loss (1.74 dB) 3-pole Butterworth distributed filter operating in the Ka-band with a center frequency of 29 GHz. The filter has a compact 6 mm square footprint and is designed using 3-dimensional (3D) micromachined integrated coax. The integrated coax transmission lines are made of forty-one nickel layers and fabricated using a selective electrochemical metal deposition process (EFAB/spl trade/). Full-wave simulations of the filter using Ansoft HFSS show very good agreement on insertion loss compared with measured results. Using the EFAB/spl trade/, we have been able to produce low-loss, all-metal, completely shielded transmission lines with small bend radii and no inter-line coupling.

A Simple Ultra-Wideband Suspended Stripline Bandpass Filter With Very Wide Stop-Band

Abstract: This letter introduces a simple ultra-wideband suspended stripline filter with a pass-band from 3.1 to 10.6 GHz and a very wide stop-band up to more than 25 GHz. The filter is realized by capacitive coupling of a quasi-lumped low-pass filter to the I/O ports. Insertion loss in the pass-band is better than 0.5 dB. The filter has a length of 13.8 mm. Excellent agreement is achieved between measured and simulated results.

DC-Link Control Filtering Options for Torque Ripple Reduction in Low-Power Wind Turbines

Abstract: Small wind energy conversion systems (WECSs) are becoming an attractive option for distributed energy generation. WECSs use permanent-magnet synchronous generators (PMSGs) directly coupled to the wind turbine and connected to the grid through a single-phase grid-tie converter. The loading produced on the dc link is characterized by large ripple currents at twice the grid frequency. These ripple currents are reflected through the dc bus into the PMSG, causing increased heating and ripple torque. In this paper, the PMSG inverter is used to control the dc-link voltage. In order to avoid reflecting the ripple currents into the PMSG, the feedback dc-link voltage is passed through a filter. The Butterworth filters, notch filters, antiresonant filter (ARF) and moving average filter (MAF) are considered. For a fair comparison, formulas are provided to tune the filter parameters so that dc-link voltage control will achieve the selected bandwidth. The different filtering options produce different levels of torque ripple reduction. The notch filter, ARF, and MAF obtain the best results and there is a tradeoff between the filter implementation complexity, bandwidth, overshoot, and the torque ripple reduction. Simulations and experiments using a 2.5-kW PMSG turbine generator validate the proposals.

A comparison of τc and τpmax for magnitude estimation in earthquake early warning

Abstract: [1] We determined the τc and τpmax parameters from the K-NET strong motion records of 16 earthquakes in Japan with moment magnitude (Mw) ranging from 6.0 to 8.3. A 0.075 Hz high-pass Butterworth filter was applied for determination of τc based on our previous studies. It was found that different pole selections of the Butterworth filter lead to different uncertainty in magnitude determination. Our results show that using two poles in the filters results in the best magnitude estimates, i.e., minimized the standard deviation in magnitude determination in comparison to Mw using τc. The τpmax parameters (Allen and Kanamori, 2003) were also determined with the same dataset using the Wurman et al. (2007) procedure. It was found that τpmax values obtained from this dataset, and using the Wurman procedure, had a larger uncertainty. However, when a 0.075 Hz high-pass Butterworth filter with five poles was added, the uncertainty in τpmax-derived magnitude estimates decreased minimizing the standard deviation in magnitude determination using τpmax. This difference in the behavior of τc and τpmax can be used to further reduce the uncertainty in rapid magnitude determination for earthquake early warning. When the magnitude estimations from τc and τpmax of each event are averaged to provide a new magnitude estimate, the standard deviation in magnitude estimates is reduced further to 0.27 magnitude units.

New Wilkinson Power Dividers and Their Integration Applications to Four-Way and Filtering Dividers

Abstract: This paper involved developing two (Type I and Type II) equal-split Wilkinson power dividers (WPDs). The Type I divider can use two short uniform-impedance transmission lines, one resistor, one capacitor, and two quarter-wavelength ( \(\lambda/4 \) ) transformers in its circuit. Compared with the conventional equal-split WPD, the proposed Type I divider can relax the two \(\lambda/4 \) transformers and the output ports layout restrictions of the conventional WPD. To eliminate the number of impedance transformers, the proposed Type II divider requires only one impedance transformer attaining the optimal matching design and a compact size. A compact four-way equal-split WPD based on the proposed Type I and Type II dividers was also developed, facilitating a simple layout, and reducing the circuit size. Regarding the divider, to obtain favorable selectivity and isolation performance levels, two Butterworth filter transformers were integrated in the proposed Type I divider to perform filter response and power split functions. Finally, a single Butterworth filter transformer was integrated in the proposed Type II divider to demonstrate a compact filtering WPD.