Hi everyone, Need some help with this problem. I need to design a low-pass active filter circuit such that its roll off attenuates frequency components at 14kHz or more by more than 17dB, Also it is desired to have the passband gain positive that doesnot deviate from 40dB by more than 3dB, The passband frequency needed is 280Hz and below.
Hope that someone can help me ASAP . Thanks.....
Sounds like standard filter in filter handbook.
Bill
-- Ferme le Bush
tq bill will look it up.....
From 280Hz to 14kHz is 5.6 octaves. Even a simple RC passive filter at 6dB/oct will give 30dB. You also want a 40dB gain so filter first and then use an opamp to get a "flat" gain. Usually standard filter have 0dB gain in band because all the gain available is better left for the feedback loop to increase precision.
Or
Connect input to OpAmp + Connect 1k from OpAmp - to GND Connect 100k from OpAmp - to OpAmp Output Connect 4,700pF across the 100k
This will give a 3 dB bandwidth of 339Hz and still provide 30dB less gain at
14kHzMG
Thanks a lot MG.......
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