[sdiy] OTA to voltage-control resonance?

[Antti Huovilainen]

On Mon, 31 Aug 2009, Antti Huovilainen wrote:

> With real devices the results may not be as good as the matching is not 
> exact. It's obvious that changing Ictrl does reduce the effectiveness of 
> the method significantly although it's still an option worth 
> considering.

Quick addition: By dividing the input resistors by 10 (4.7k/22, still 
easily driven by an opamp) and increasing the second OTA input divider to 
4.8k/22, the overall distortion can reduced by 2-4x at the expense of 
increased distortion at unity gain (to 0.3%/0.1% for 10V/5V signal).

Antti

"No boom today. Boom tomorrow. There's always a boom tomorrow"
   -- Lt. Cmdr. Ivanova