[sdiy] Passive filters and impedances

[Richie Burnett]

> Anyway - has this impedance scaling technique ever been used to full
> extent in any ladder filters, using different capacitor values for all
> stages?

You mean used in diode or transistor ladders?  I suspect not, as usually all 
of the diodes or transistors operate at the same bias current, and would 
therefore exhibit *the same* incremental resistance.  Not a decade apart.

It works great for passive designs like what Tom W originally asked about 
though.  I've used fixed 2nd and 3rd-order un-buffered passive RC filters 
for things like cheap and dirty PWM control signal filtering and 100Hz/120Hz 
ripple removal from signals in electronic products.

-Richie,