Wanted:High freq osc

[Magnus Danielson]

From: "Paul Maddox" <noxons at btinternet.com>
Subject: Re: Wanted:High freq osc
Date: Sat, 7 Oct 2000 17:39:25 +0100

Hi!

>  The ASMVCO will go upto about 600Khz, though its will need some HF comp
> adding.

Um, the ASM-1 VCO does have a HF comp, but it migth need rescaling if
you change the capacitor.

The scaling follows the rule

RC = t
      reset

So, the series resistor (R) is given its value as a result of the
integrator capacitor (C) and the time it takes to reset the capacitor
through the transistor. The formula is:

    t
     reset
R = ------
      C

It is fairly easy to show that this HF compensation can be made
perfect if the above relation is set.

By selecting a good transistor, the required reset time can be made
shorter, but the reset-curcuits time constant must be adjusted. The
reset curcuit must keep the transistor enabled slightly longer than it
takes to actually reset, the time-margin is needed to ensure that one
really does have a full reset under all conditions.

Given a stable reset, the full reset time is then used in the
compensation calculation.

Cheers,
Magnus