[sdiy] integrator / capacitor leakage

[René Schmitz]

Hi Achim, Jürgen and all,

ASSI wrote:
> On Dienstag, 6. Dezember 2005 10:21, jhaible at debitel.net wrote:
> 
>>Are there chips out there which do this? I don't want to start
>>programming, so the obvious solution, DSP with on-chip ADCs and
>>DACs, won't help me much.
> 
> 
> I don't think these are working directly down to the mHz region, but it 
> seems you'd need a DDS (direct digital synthesis) chip given those 

The ones I have played with (AD9852, AD9835) worked down to audio 
frequencies, and there is no reason why they shouldn't work down to the 
minimal programmable frequency if the output circuitry is DC coupled.
There are some that have a direct quadrature output, which would be
handy.

> constraints. You still need a processor somewhere to load the control 
> words into the DDS chip. Operation down to mHz involves of course 
> another mixer... check

The really tricky part is a decent external interface anyway. I mean 
setting a single frequency would be one thing, but I guess one would 
also want voltage control for example.

> http://www.sander-electronic.de/be00005.html
> 
> for available IC.

Not exactly cheap either.

Cheers,
  René

-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159