On Mon, 27 Jan 2014, John Larkin wrote:

On Mon, 27 Jan 2014 10:18:27 -0500, Michael Black wrote:

On Mon, 27 Jan 2014, RobertMacy wrote:

This is a simple switched capacitor filter made by National. Would somebody
send me a copy, or at least provide a URL that HAS it!!! and not datasheet or
alldata crap! If AppNote available that too please.

Have you got the part number right? National's first generation filter
like that had some other prefix (I can't remember what, I'd know the minute I
saw it). I'm thinking "MFC" but I don't know why. It didn't start
with National's traditional prefix, "LM". Maybe later they used some other
prefix, but I'd double check.

National's classic switched-cap filter was the MF10, metal-gate CMOS. There was
a later poly-gate version, can't remember the part number.

Yes, that's what I was remembering.

Overall, switched-cap filters weren't all that great. OK for some apps, but they
were really noisy, and aliased anything available, including power supply crud.

It's one of those things that were transitory, like charge coupled delay
lines. Fill in a gap, relatively late, that soon could be done by
converting to digital and doing the work there.

Michael

I once designed a double-conversion superhet FSK modem full of MF10s, for
Reuters' landline newswire service. Sold a few before PCs and the Internet made
the classic newswire thing obsolete.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation