[time-nuts] Component level 1:2 splitter

Bruce Griffiths bruce.griffiths at xtra.co.nz
Mon Mar 10 18:02:01 EDT 2008


randy warner wrote:
> Guys,
>
> I need to come up with a 0db little splitter to route 1 antenna into 2 GPS
> receivers. To keep the isolation up I want to use an active splitter instead
> of a passive one. I suppose I could use a passive splitter followed by two
> LNA's (one to each receiver), but I would then have to add a lot of
> attenuation to knock the signal back down. I suppose it would work, but the
> noise factor sure wouldn't be optimum.
>
> Does anyone out there know of a single/dual IC solution to this? Everything
> I have found LNA wise is in the 10-30 dB range. Note that this will be a
> board mounted circuit and I don't have to worry about connectors, etc. I'm
> hoping to find a little solution that I can cover with one of Laird's
> standard shield cans.
>
> Thanks,
>
> Randy Warner
>   
Randy

The only solution that springs to mind is to amplify split/attenuate 
amplify attenuate.
If one uses low noise amplifiers and maintains a net gain before the 
output attenuator then the noise figure can be kept reasonably low.
This requires an input amplifier followed by a splitter and possibly an 
attenuator followed by an amplifier with an output attenuator for each 
of the 2 splitter outputs.
The output attenuators will also increase the isolation by a few dB.

Bruce



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