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Topic: Active filter

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	Active Filters
		The two outputs from the LR2 crossover filter are 180 degrees out of phase at all frequencies, which requires to use one of the drivers with reversed polarity, so that the two acoustic outputs add in phase.
		The acoustic frequency and polar response is controlled by the electrical filters and the response of the mounted drivers.
		A first order allpass filter section with flat amplitude response but phase shift that changes from 0 degrees to -180 degrees, or -180 degrees to -360 degrees, is often used to correct phase response differences between drivers.
	www.linkwitzlab.com /filters.htm (0 words)

	Monolithic IC general purpose active filter - Patent 4417214
		The filter blocks may be tuned according to external resistance ratios and/or according to the frequencies of the external clock signals.
		An active filter according to claim 1 wherein the filter building blocks and the clock interface means are made of MOS components.
		An active filter according to claim 1 wherein the filter building blocks, the clock interface means and the input/output means are mounted in a dual-in-line package.
	www.freepatentsonline.com /4417214.html (3600 words)

	High Performance Active Harmonic Filter
		This type of filter is connected in series with the AC distribution network and compensates both the harmonic currents generated by the load and the voltage distortion already on the AC system.
		The Active Filter is connected in parallel with the AC line, and constantly injects currents that precisely correspond to the harmonic components drawn by the load.
		Easy to implement, an active filter may be installed at any point on a low voltage AC system to compensate the power drawn by one or several non-linear loads, thus avoiding the circulation of harmonic currents throughout the low-voltage AC system.
	www.activeharmonicfilters.com /High_Performance_Active_Harmon/body_high_performance_active_harmon.html (1408 words)

	Active Filters
		Active filters can be built on the microelectronic scale without the use of large and inaccurate inductors.
		Since active filters tend to have high input impedance and low output impedance, multiple filters can be placed in series without seriously affecting the performance of the individual filters.
		With this filter, the differential equations solution technique of state variables is used to obtain low-pass, high-pass, and band-pass filters are all at once.
	www.engr.sjsu.edu /filter/Proj_sp2ka/act_fil_cosper_fold/act_fil_cosper.htm (1175 words)

	Schematica Software 555 timer and active filter circuit design and simulation
		Meet your active filter requirements with this user-friendly and versatile design software.
		Enjoy a powerful schematic capture and simulation application specifically designed for the ultra fast rendition and simulation of frequency shaping analog circuits such as preamplifiers, amplifiers, active filters, passive filters, crossovers, equalizers and tone controls.
		Contains everything in 555 Timer PRO plus many additional and useful design wizards, including order 2 to 6 lowpass, high pass, bandpass and bandstop active filters with stable multiple-feedback implementation, op amp and transistor amplifiers, photodiode amplifiers, tone decoding, voltage references, voltage comparators, counter IC configurations, and best pair resistor selection...
	www.schematica.com (257 words)

	Active filter - Patent 6803812
		In the notch filter, an output of an operational amplifier is fed back to an inverting input terminal thereof through a second voltage dividing circuit and a charge/discharge resistor.
		In an active filter there are filters of various types and well used one thereof is a circuit of type so called Delyiannis-Friend.
		In order to attain the above object, according to a circuit construction method of an active filter of the present invention, an active filter having a low pass notch filter is constructed by using an operational amplifier, two capacitors and three voltage dividing circuits based on the following idea.
	www.freepatentsonline.com /6803812.html (1900 words)

	Active filter patent invention
		[0012] An aim of the present invention is to make-available an active filter in which the non-ideal effects due to the parasitic poles introduced by the amplification stages utilised are compensated for.
		A still further aim of the invention is to provide an active filter in which the operational amplifiers are not destabilized at high frequency, due to the compensation itself.
		[0019] The active filter in accordance with the present invention is identified with reference numeral 1 in the accompanying figures.
	www.freshpatents.com /Active-filter-dt20060907ptan20060197587.php (1106 words)

	Filter Design Guide
		In a classic, passive filter made of inductors, capacitors, and resistores, the filter's frequency response is the result of the impedance of inductors and capacitors changing with respect to one another, and with respect to the resistors in the filter.
		The poles of a two-pole filter are at ±45°.
		The blue graph is a two-stage (four-pole) active low-pass filter, the pink is a single-stage (two-pole) active filter, and the yellow is a one-and-a-half stage (three-pole) filter.
	alignment.hep.brandeis.edu /Electronics/A2037/Filter.html (5610 words)

	Active Filters by Nuhertz Technologies
		Filter Solutions provides you with a flexible means to update your Active Filter elements values with the nearest value from your available standard parts, or to the nearest 1%, 5%, 10%, or 20% standard industrial value.
		Active filters in an integrated environment use resistors that capacitively interact with the backplane resulting in parasitic capacitance associated with each resistor.
		Filter Solutions allows the user to apply the desired amount of lumped parasitic capacitance at each end node of each resistor and will apply this parasitic in the analysis of the filter for easy viewing of the parasitic effect.
	www.filter-solutions.com /active.html (3195 words)

	Active Filter Workshop
		Active Filter Workshop is a suite of filter-design utility programs designed to operate in the Windows* environment.
		While Active Filter Workshop is primarily intended to be used by loudspeaker designers who need to design complementary electronics (crossovers, equalizers, etc.) it should have numerous other uses in engineering and education.
		Active Filter Workshop tries to provide the user with as much insight as possible by providing detailed schematics and showing the math necessary to determine component values.
	ourworld.compuserve.com /homepages/f_ostrander/afilterw.htm (820 words)

	Active Notch Filter 50/60Hz
		Filter automatically synchronizes to any frequency between 47 to 70 Hz.
		The principle behind the EDR 82534 is to reduce line interference using multiplexed sampling of “hum” with a series of capacitors charging to the hum level, and subtracting that level from the overall signal.
		Because the polarity of the voltages across the respective capacitors opposes the hum voltage in the signal, the portion of the hum voltage appearing at the output is the hum voltage minus the previously “stored” capacitor voltages. The remaining interference consists of high frequency signal components.
	www.vsholding.com /ActiveNotchFilterNotes.htm (421 words)

	Active Filter Four
		This filter board resulted from my looking for an active filter board at the same time as Jens felt like designing a board.
		It was designed as a flexible crossover board with features not often found on DIY boards.
		Fourth order filter sections can be combined with notch filters to create Cauer-Elliptic filters.
	mysite.verizon.net /vze3xvxs/audio/id20.html (269 words)

	Abstract:
		For most applications, active filters are easy to design and they eliminate the need for high-cost inductors.
		The result filter, however, will not have a frequency response like the ideal one, but will be like that shown in figure 2.
		Generally, active filters use components or devices that are able to amplify, such as transistors or Op Amps.
	ite.gmu.edu /~aaljassa/ece464/project.html (928 words)

	K&N Filters, K&N Air Filter, KN Filter, KN Filters, K&N Cold Air Intake, K&N FIPK
		The facility has dynamometers to ensure that every K&N air filter, K&N oil filter and K&N cold air intake and are technically designed for the highest increase in horsepower possible.
		KandN Air Filter Purchase a new K&N air filter designed to achieve virtually unrestricted air flow while maintaining filtration levels critical to ensure extended engine life.
		The K&N Filter high flow cotton gauze air filter is washable and reusable.
	www.activepowerfilters.com (0 words)

	Circuit Sage: Filter Design and Analysis
		Active filter designer (mirror) and HF filter design by John Owens.
		PCFilter, Active filter synthesis from Michael Ellis, $325, includes his book on filter synthesis.
		Elsie, a filter design routine by Jim Tonne, $275, student version is free.
	www.circuitsage.com /filter.html (1081 words)

	Schematica's Filter Wiz PRO active filter design software
		Filter Wiz PRO active filter designer version 4 has just been released.
		Filter Wiz PRO can be freely downloaded for evaluation, without time restriction.
		This is the opening window of Filter Wiz PRO - where the active filter type (lowpass, highpass, bandpass, bandstop or user-defined) is selected, and the active filter specifications are entered:
	www.schematica.com /filter_wiz_files/FWPRO.htm (458 words)

	Programmable/tunable active rc filter patent invention
		Integrating the filters into one chip is a common trend in the manufacture process of the advanced integrated circuit, especially to the communication markets.
		In general, the programmable active RC filters finely tune the value of the cut-off frequency by adjusting the number of operative cells of the resistance or the capacitance.
		Since each of the capacitors is connected in parallel, so that the equivalent capacitance of the filter circuit can be obtained by adding the capacitance of the capacitors connected with the switch devices b0, b1, b2, b3 that is operative.
	www.freshpatents.com /Programmable-tunable-active-rc-filter-dt20060824ptan20060186952.php (1197 words)

	Electrolux plc
		They said that during the operation of the Twin Clean, air from the cyclonic chamber entered the active chamber, passed through the active filter and deposited microscopic particles on to the exterior surface of the filter.
		They said during the cleaning process a minute amount of dust removed from the filter in the cleaning chamber was deposited on the active filter as the air was expelled to the exhaust filter but because it was only a minute proportion of the total dust removed, it was of little consequence.
		We noted the user had to lift up and switch the filters then turn one 360 degrees to "clean" the filters when it was time to clean the active filter.
	www.asa.org.uk /asa/adjudications/Public/TF_ADJ_41938.htm (2322 words)

	Analog Devices: Interactive Design Tools: OpAmps :
		Filters are initially specified by overall type and function in the first gray region at the top of the applet.
		Up to 8th-order filters can be designed with this tool, and since each stage can have a pair of complementary poles, 1-4 stages are displayed.
		The ideal and component-modified system responses are both plotted: green for the magnitude and red for the phase with the component-modified response in darker colors and usually hidden behind the ideal plots.
	www.analog.com /Analog_Root/static/techSupport/designTools/interactiveTools/filter/filter.html (649 words)

	Wireless Design & Development (Site not responding. Last check: )
		The HF Active Filter employs patented high-speed op-amps and advanced thick film technology, which allows flexibility in design, fast turn-arounds of new engineering samples, and ease of smooth migration from simulation to product.
		The smaller size of the component reduces the size of a passive filter solution by 50% and a discrete active filter solution using discrete high speed op-amps also can be quite large compared to the HF Active Filter.
		The HF Active Filter offers to eliminate many of the parts on the board by puling all of their functions into a single package.
	www.wirelessdesignmag.com /ShowPR.aspx?PUBCODE=055&ACCT=0012660&ISSUE=0104&RELTYPE=PR&PRODCODE=E1080&PRODLETT=A&CALLFROM=RELPGM (280 words)

	Introduction to Filters (Site not responding. Last check: )
		This document is an introduction to frequency response, and an introduction to active filters (filters using active amplifiers, like op amps).
		Besides low-pass filters, other common types are high-pass (passes only high frequency signals), band-reject (blocks certain signals) and band-pass (rejects high and low frequencies, passing only signal areound some intermediate frequency).
		There is a special type of active filter, the switched capacitor filter, that takes advantage of integration to achieve very accurate filter characteristics that are electronically tuneable.
	www.swarthmore.edu /NatSci/echeeve1/Ref/FilterBkgrnd/Filters.html (1211 words)

	Active Filter - Product Information
		GE Digital Energy Active Filter represents the state of the art in power electronic equipments, principally dedicated to UPS applications, for an effective current harmonic mitigation and power factor correction.
		The result of this combination passive/active filters gives the best performance in terms of harmonics compensation and power factor correction, with a negligible effect on the total UPS system efficiency.
		Active Filter can also be used as stand alone for any other power electronic equipment, provided that the load is symmetrical and not supplied by a IT power distribution system.
	www.geindustrial.com /cwc/Dispatcher?REQUEST=PRODUCTS&pnlid=8&famid=46&catid=1661&id=activefilter (287 words)

	Active Filter Design
		Thus, sampling at 500 KHz, you should design the filter's passband corner frequency to be in the region of 150 KHz to 200 KHz depending on your "non-aliased" dynamic range requirement.
		In this case, you build the filter as a single assembly using the data in Zverev, et al, without having to break the polynomial into pole pairs.
		You need only one elegant filter at the input of your sampler; a simple filter at the output of each down-converter will be sufficient for each of those sub-assemblies.
	www.amsat.org /amsat/archive/amsat-bb/200401/msg00580.html (468 words)

	A Filter Primer - Maxim/Dallas
		A type of filter that is common to many applications requires a response that is flat in the passband but cuts off as sharply as possible afterwards.
		Butterworth and Chebychev filters with sharp cutoffs carry a penalty that is evident from the positions of their poles in the s plane.
		Note that all the filters described have the same number of zeros as poles (this must be the case, or the transfer function would not be a dimensionless expression).
	www.maxim-ic.com /appnotes.cfm/appnote_number/733 (3812 words)

	Power factor improvement using active filter for unbalanced three-phase non-linear loads (Site not responding. Last check: )
		In this paper, a modified shunt active filter is used under unbalanced three-wire supply voltages with non-linear loads.
		The main objective of the proposed shunt active filter is to control the three-phase supply currents both in its waveform, magnitude and phase to follow three-phase reference signals.
		The proposed shunt active filter control strategy is based on hysteresis control, which is very simple to implement and does not even require any measurement of the load demand.
	www.inderscience.com /search/index.php?action=record&rec_id=8551&prevQuery=&ps=10&m=or (324 words)

	DNK Amazon Store :: Active Filter Cookbook, Second Edition
		This Don Lancaster classic is by far the best-selling active filter book of all time.
		Lancaster's Active Filter Cookbook includes practical elements such as working circuits, ready-to-use design tables, tuning, and real-world applications, making it easy to use and apply.
		I am ordering another copy of the "Active Filter Cookbook" because I gave away my other copy to an engineer in Asia (while on a business trip) who desparately needed it.
	www.entertainmentcareers.net /book/ProductDetails.aspx?asin=075062986X (586 words)

	Analog Devices : Rarely Asked Questions (RAQs) : How Not to Design Active Filters (Or Not Only Sharks Distract Divers)
		One of my fellow divers, Ekaterin from Russia, had just designed an active filter with ADI op amps, was having some problems, and recognized the logo.
		Since many active filter topologies use capacitive feedback it is unwise to design active filters with them.
		After solving the active filter problem, we both returned to the water, and the beautiful reef life, with no more distracting thoughts of work.
	www.analog.com /analog_root/static/raq/raq_activeFilters.html (597 words)

	Mini Active Filter Modules Product Overview
		The latest active devices (not switched capacitor devices) are used to build the filter meaning that it is extremely stable with temperature and that it has ultra-low noise and distortion.
		The Time Delay filter is the best choice for transient filtering and for applications where preservation of time domain wave shapes is essential.
		It is a tightly controlled filter with typically less than 0.1° of phase mismatch between channels to the cutoff frequency.
	www.pfinc.com /products/modules/filter_decription.htm (520 words)

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