[Laser] SD3084 photodiode

[F1AVYopto at aol.com]

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. 
73 Yves  F1AVY