[Ronja] new receiver design

[mohamad al-jamal]

hey guys

the receiver is working just fine ... with 220K feedback resistor SNR is
enhanced dramatically ... the output of the TIA without an optical signal
was reduced to 5mV p-p .. and the signal was about 400mV p-p .. the range
was increased by a factor of 25% (without lenses ) .. i forgot to tell you
that we have modified the transmitter as well . we used a cheap IR LED from
vishay TSFF5210 (http://www.vishay.com/docs/81090/tsff5210.pdf) .. this
image illustrates the new configuration ..

http://img100.imageshack.us/i/txfinal.jpg/

i need your comments please .

On Tue, Apr 6, 2010 at 6:13 PM, Karel Kulhavy <twibright at hispeed.ch> wrote:

> ---- "Gullik Webjörn" <gullik.webjorn at corevalue.se> schrieb:
> > Hello Mohamad,
> >
> > It is interesting to see people working on implementing the
> > design with more modern components. How is your design performing?
> >
> > Have you compared sensitivity vs. noise against the standard frontend?
> >
> > What bandwidth are you getting?
> >
> > As for R3 in your schematic, if forms a pole with the 100 nF, at below
> > a khz, so the noise contribution from R3 should be minimal in the band
> > of interest, Mhz, I believe. The BPV10 is a good one, OPA905 is also a
> > useful PIN, and readily available.
> >
> > I think you should be *very* careful with filtration of supply voltages,
> > after all you will be building a high bandwidth "straight receiver" so
> > the risk of unwanted feedback is there all the time. Shielding will be
> > required, you will be running 120 + dB gain in the entire chain.
>
> Yeah, Ronja has about 120dB gain, more than the first telecommunications
> satellite
> (Telstar, 100dB) :)
>
> Karel
>
> >
> > Good luck,
> >
> > Gullik
> >
> >
> > On Sun, 2010-03-28 at 06:04 +0300, mohamad al-jamal wrote:
> > > Dear all
> > >
> > > I have been trying to modify the Ronja inferno receiver for the sake
> > > of better performance .. i have replaced the first stage
> > > ( transimpedance amplifier ) with a conventional configuration : an
> > > opamp with an RC feedback circuit .. instability is avoided by
> > > inserting a relatively high capacitor in the feedback circuit .. the
> > > bandwidth is ruined though , therefore the NE592 is used - just like
> > > in inferno - to compensate for the integrator effect of the TIA . i
> > > used a high bandwidth opamp from texas instruments (OPA657) . and used
> > > another PIN photodiode , a cheap one from vishay
> > > (http://www.vishay.com/docs/81503/bp10nf.pdf) . the PIN is directly
> > > biased by a -12 supply . and every thing went just fine !! the signal
> > > was nice and clean . i'am still experimenting , but it seems
> > > promising .  this image illustrates the new configuration .
> > > http://img265.imageshack.us/i/rxfirststage.jpg/
> > >
> > > i have a couple of questions though :
> > > regarding R3 in the schematics , i thought that R3 should be as high
> > > as possible in order to avoid thermal noise ... is that true ?
> > > regarding the filtration practice of the supply connected to the PIN ,
> > > is the configuration in the image sufficient ?
> > >
> > > any ideas are highly appreciated .
> > >
> > >
> > >
> > >
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> >
> >
> >
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