[sdiy] Passive filters and impedances

[Donald Tillman]

> On Nov 4, 2015, at 3:30 AM, Mattias Rickardsson <mr at analogue.org> wrote:
> 
> Anyway - has this impedance scaling technique ever been used to full
> extent in any ladder filters, using different capacitor values for all
> stages?

That's a very interesting question.  Okay, here is a research project:

Given a 4 pole RC ladder filter, intended to be used as a Diode Ladder VCF so all the R's are the same value, find which capacitor values minimize the ratio of highest to lowest pole frequencies.

Assume no second order effects such as input impedance and output impedance.  You'll probably want to keep the product of the capacitor values constant.

Go for it!

  -- Don

--
Don Tillman
Palo Alto, California
don at till.com
http://www.till.com