[Laser] SD3084 photodiode

[Chuck Hast]

On 5/12/07, F1AVYopto at aol.com <F1AVYopto at aol.com> wrote:
> Chuck,
> You wrote :
> >Yves:
> >How  FAST will it go? That is my question, I am looking for diagrams  of
> >receivers that will go fast for high speed data. Mine is a compromise
> between
> >sensitivity and speed.
> This receiver was designed to receive  less than 100 nS low rate pulses.
> Its bandwidth is about 20 MHz but a ringing  effect is used to enlarge the
> pulses and the HF envelope is AM detected and  integrated before to be FFTDSP
> extracted in the audio spectrum.
> So this RX is  absolutely not matched for digital high speed communication.
> For digital  communication may be you can use the schematic at  :
> http://pageperso.aol.fr/F1AVYopto/opto/FIG8.jpg
> It is a high speed  device with more than 50 MHz bandwidth capability.
> With an APD you have not  to do a compromise between sensitivity and speed
> but you have to control the  high voltage PSU with a sophisticated temperature
> compensation.
> You can also  adjust the high voltage PSU versus the receive signal envelope
> as a feed  back.
> This diagram is very simple but in spite of the small components count  it is
> mandatory to use a copper layer to isolate the components from the wiring
> tracks and so avoid oscillations.
> This schematic is inspired from an old  DAVID JOHNSON AND ASSOCIATES one but
> I think it can be adapted with  compatible new CMS components.
> It must be follows by a threshold  detector or a Schmitt trigger to interface
> with the com logic.

Thank you. I had not really thought so much about APD's initially but looks
like in the end that is the real way to go for these links,
particularly the long
haul ones. Tnx again...

-- 
Chuck Hast  -- KP4DJT --
To paraphrase my flight instructor;
"the only dumb question is the one you DID NOT ask resulting in my going
out and having to identify your bits and pieces in the midst of torn
and twisted metal."