Tom --

My $0.02...

I don't think this is the filter you were using, but Maxim has a family of
filters that don't need to be programmed but use an external clock to set
the cutoff frequency.  Often, the cutoff is 100:1 lower in frequency than
the clock.  There is very little attenuation at the clock frequency, so a
simple analog filter is needed too.  See

http://dbserv.maxim-ic.com/pl_list.cfm?filter=f

I can say about the ones you were using, but one problem with integrated
filters such as Maxim's is drift and low-frequency noise.  In these
filters, the signal path goes through the IC.  Some integrated filters are
designed so that they are in parallel with and shunt a signal source to
effect the desired filtering.  That takes care of the drift problem but not
the low-frequency noise.

Karl

At 08:46 AM 4/18/2000 -0400, you wrote:
>Second.  There is a new chip that is up to a 6 pole analog filter.   The
>configuration of the filter is set in a device similar  to an EPROM burner.
>The software that comes with it has full design features such as  simulation
>of amplitude and phase.  Unfortunately I threw the flier away but I am
>trying to find the manufacturer through other channels.   This could be
>helpful in designing filters for local noise.  If anyone knows the web site
>of the manufacturer please let me know.  I will continue to try to find it
>by other sources,

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