[sdiy] tri-sin shaper and THD

[ryan williams]

harrybissell wrote:
> Woah. Nice work !!!

thank you! and Ian.

> I tried spice simulation with and without feedback.  My proggy
> said the non-feedback case was about 3.5% THD and the feedback
> case was about 1.05%.
> 
> That seems to coincide well with your data.

That sounds close enough. I did not come up with a method to find the 
best amplitude yet. When doing these calculations, I first pick 
something that looks good, then adjust to make the THD as good as I can 
by making small changes and looking at the result. So, that explains why 
I did not see the other low distortion point. With feedback it wasn't 
much more difficult.

> Theer was some discussion in Electronotes (there it is again) about sine
> conversion that was using an OTA for most of the conversion, then a
> clipper to flatten the cusp.

thats a good idea. I'll have to try and simulate this one too. if only I 
wasn't in the middle of a 25page EE report that's due tommorow...

-ryan