data filter - RF Cafe Forums
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Post subject: data filter
Unread postPosted: Mon Mar 28, 2005 3:09 pm
I'm looking for an active filter for my 10kbps TTL data line.
Any ideas what the lowest possible Fc can be for the filter? Any suggestions for MFG's of such filters?
Post subject: Data Filter
Unread postPosted: Tue Mar 29, 2005 1:47 pm
The answer to your question probably comes from several other questions:
1. Why do you want a filter at all?
2. Where is the data going?
3. How much stop-band attenuation do you really need?
4. How much are you willing to pay for the very narrowest possible bandwidth?
The (unattainable!) limit would be 5 kHz. Any reasonably narrow filter will either require a phase equalizer to remove inter-symbol interference, or be many stages of (approximately) linear phase filtering, such as Bessel filters.
Most filters are either custom-made (read $$$) or do-it-yourself with building blocks from an IC company such as Linear Technology (www.linear.com). LTC offers free design software for their chips.