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Question on setting an orde at passive filter to infinite

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zhi_yi

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infinite orde filter

hi there, please help me..

if we have a filter, for instance at orde 2 low pass filter with one part of it is active fitler with integrator, and another is passive RC filter, if i add the orde of the filter at passive filter to infinite, is it possible to get an ideal response of low pass filter? if not, please tell me why?

thanks..
 

Sceadwian

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infinite orde filter

I don't think this is possible with an analog filter, the components used will always cause an non-ideal responce no matter how many poles are used. Digital filters can come pretty close to approximating an ideal low/high/bandpass though using good resolution FFT.
 

Kral

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Re: infinite orde filter

zhi_yi,
The more poles you have in a filter, whether it's active or passive, the closer you get the the ideal "Brick wall" filter characteristic. However, this characteristic can not be attained in practice. The ideal filter theoretically has a non-causal response, which means that it responds to an input that has not yet occured.
Regards,
Kral
 

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