[sdiy] some diy: ssm2040 filter

[Antti Huovilainen]

On Mon, 5 Sep 2005, ryan williams wrote:

> second:  the DC offset at each stage's output changes about 3.5V as the 
> OTA bias current is increased.  Actually, this change is only happening 
> at stages 1 and 3.  stages 2 and 4 have a small change, something like 
> .2V.

This is probably due to the cheapo two-transistor current mirrors used. My 
guess is that since the stages are more or less matched in the actual IC 
and each stage is inverting, the offsets cancel out.

Antti

"No boom today. Boom tomorrow. There's always a boom tomorrow"
   -- Lt. Cmdr. Ivanova