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Digital adjustable brick wall low pass filter
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OgreVorbis:
Hi,
I am in need of an adjustable brick wall filter. I'd actually prefer a studio style rack mount unit, but it looks like this is going to have to be something I build myself because I can't find anything.
I plan to use this chip: https://www.digikey.com/product-detail/en/maxim-integrated/MAX294CPA/MAX294CPA-ND/1512387
And to generate a clock signal for it using Si5351A to adjust the corner frequency.
Is this a good way to go about doing this? Will there be noise from the clock signal? Is it stable enough?
Maybe there is already a directly programmable filter out there, so I eliminate the need for the clock?
ledtester:
I would just try it. The chip is advertised as "easy to use", and "no external resistors or capacitors required" so there shouldn't be a lot of complications.
Be sure to read page 7 of the datasheet especially the section "Uncommitted Op-Amp" - it can help with clock noise filtering among other things.
A google book search for "max293 circuit" got some hits in "Analog Circuits Cookbook" by Ian Hickman, so checking that out might help.
ledtester:
For more discussion on aliasing, have a look at the section "SAMPLED DATA SYSTEM CONSIDERATIONS" from the MF-10 datasheet (p. 26):
https://www.ti.com/lit/ds/symlink/mf10-n.pdf
coppercone2:
those digital smfilter chips usually have a clock noise spec some where.
I want to say LT used to sell the same chip or something based on the same die, so you can find the LT equivalent to see if its not there
it says clock feed through 5mVpp
they have continous time filters too, but the impedances tend to be high.
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