[sdiy] More Passive filter stuff

[Magnus Danielson]

From: Haible Juergen <Juergen.Haible at nbgm.siemens.de>
Subject: [sdiy] More Passive filter stuff
Date: Tue, 27 Feb 2001 14:35:36 +0100

> More questions:
> 
> Are there passive filter topologies that are more tolerant to impedance
> mismatch than others ?

Not to my knowledge, but there are topologies that are more or less
dependent on the actual values of individual components. The term to
look for is sensitivity.

> I'm aware that passive filters require a certain load impedance
> for their nominal filter response. Is there something like a tradeoff of
> "mismatch tolerance" and filter order for a certain required
> steepness, or is impedance mismatch a knockout factor from the start ?

Well, if you talk sufficiently RF, then impedance matching is where
you start. The theory behind it is that you use matching impedances in
order to acheive maximum power transfer (forget the voltage stuff,
that is a LF/audio property). Sufficiently large impedance missmatch,
and frequency curve isn't your main interest, you just bounce too much
energy of at the input or at the output, that the energy transmission
is way off and this is usually a BAD thing.

For me the issue is really, what are you trying to do?
What are your frequencies?
What are your impedances?

> Any good book recommendations on that topic ?

There are many of them, but there are many good books in the field.
Check out my page of synth books and one or two may show up
unexpectingly ;)

Cheers,
Magnus