Filter Design LT1251/LT1256

[Paul Perry]

At 12:45 PM 27/01/99 +0200, Mikko Helin  wrote:
I was reading some old issue
>of EW ... there was 
>a schematic of a filter built around some Linear Technology 
>filter chip....
>(LT1256 or something like it), but it was not a swiched cap 
>filter (think I), there was a VC input, no clock inputs.

you are right Mikko, LT1251/LT1256.
40Mhz variable gain blocks.
A problem might be that the nearest supply of these to Australia is 
Digikey USA mailorder, and they will be about $A20 landed each..
but yes, the Linear databook has a nice state variable  filter
with voltage control of Q and F, using 3 of these.
Of course, it shd be possible to convert the ckt to run on AD633
multipliers.
I'd stay right away from those commercial switched cap blocks,
personally.

paul perry Frostwave P/l Melbourne Australia