[Ronja] new receiver design

[Karel Kulhavy]

---- "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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