[sdiy] equations up

[Ian Fritz]

Magnus ---

At 09:27 AM 6/15/2003, Magnus Danielson wrote:

>You formula (2) for the CCO is inaccurate. It misses out the dependence on V+
>for which also I0 depends.

The assumption that goes into Eqn. (2) is that any drift in the CCO core is 
"tuning drift".  I probably should have been more explicit about that, but 
since the emphasis of the document is on correcting converter inaccuracies 
I don't see this as an important issue.

I also assume that well-regulated, stable supplies are used for critical 
voltages.  I would never use the AMS1 design for a serious VCO without 
extensive modifications.

As far as your point on drift in I0, I do not believe that affects Eqn. (2).

>If you also toss in the scaled linjear input you
>get another term there.

I don't understand what this means.

>There are a few points to remember:
>
>* Supply voltage effects

Again, regulated sub-supplies for critical voltages are a must.

>* Certain offsets can be compensated for variating voltage, but care must be
>   taken.

I don't understand what that means either.  I think I *have* been careful, 
since I was able to get my drift to under 50 ppm/K.

>If you look at the ASM-1 homepage you will find enought hints from my work on
>this...

I don't really see anything there on temperature drift except "put in a 
tempco if you want to".  Maybe I didn't look in the right places.  Let me know.

Thanks for your interest.

   Ian