[sdiy] New Vco (new images)

[Magnus Danielson]

From: "Nils Pipenbrinck" <np at inverse-entertainment.de>
Subject: Re: [sdiy] New Vco (new images)
Date: Sat, 29 Sep 2001 01:56:23 +0200

Nils,

> > To make the tuning curve better I think I'll add that Franco compensation,
> > its not a big deal, but I need some time to redraw my circuits. I'll all
> > let you know.
> 
> Hm, I never heared about Franco compensation before.. Could someone please
> explain what that kind of compensation is nessesary for?

The Franco compensation is a method for compensating that the
oscillator goes flat when reaching for higher frequencies due to the
fixed reset time. The ingenous behind it is that the compensation
varies with the control current of the core simply by putting a
resistor in series with the capacitor. The method for dimensioning
this resistor is by the formula:

t      = R      * C
 RESET    fcomp    int

Naturally, one has to take into account resistance which is allready
in the path.

This works supprisingly well actually.

> (a search on the net just gave me a lot of spanish pages. And using the very
> little spanish I know I think they all talk about politics and not analog
> electronics.. :)

You need to know that his name is Sergio Franco. He has also written a
good book on op-amps.

Cheers,
Magnus