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Latest UHF DATA RADIO SCHEMATIC - RF Cafe Forums
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jom Post subject: Best solution for RF protection Posted: Sun Jan
11, 2009 10:13 pm
Captain
Joined: Fri Jan 26, 2007
2:40 am Posts: 14 I've got a specification that allows as much
as +20 dBm into a receive input but many LNAs can't take that much power
without ruining the amplifier. Is there some kind of diode circuit that
can be used for protection against such a RF input without creating
distortion at a reasonably lower level? My input is relatively low frequency
(1-30 MHz...HF).
Thanks
jom
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jom
Post subject: Posted: Fri Jan 23, 2009 3:18 am
Captain
Joined: Fri Jan 26, 2007 2:40 am Posts: 14 Anyone have
any ideas?
Thanks
jom
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nubbage
Post subject: Posted: Fri Jan 23, 2009 12:47 pm
General
Joined: Fri Feb 17, 2006 12:07 pm Posts: 218 Location:
London UK There are one or two bits of data missing before I can
get my addled head around this one. Is the frequency of the +20dBm
signal very close to weaker signals you are trying to detect/decode?
And is it at a fixed frequency or anywhere in the range? Is the
+20dBm signal pulsed or continuous? Are the weaker signals spread
over a random spectrum from 1-30MHz? I would certainly look around
for bomb-proof front-end amplifiers, such as the approach using transmit
transistors with a measured and adequately low noise factor as the first
stage. This approach has been shown to yield very high IP3 figures.
_________________ At bottom, life is all about Sucking in
and blowing out.
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jom Post subject: Posted:
Mon Jan 26, 2009 5:58 pm
Captain
Joined: Fri Jan
26, 2007 2:40 am Posts: 14 The frequency is anywhere in the 1-30
MHz range. This is NOT a performance spec so much as it is a "damage"
spec. Another words we don't have to receive anything in particular
while this is going on.
I think the damage spec is "continuous".
The one thing that is tough here is that most gain block amps
I see have absolute max inputs no more than +18 dBm (most MiniCircuits
amps have +13 dBm). It's hard enough just finding an amp that will work
in this range anymore (due to most focus on the higher ranges) let alone
an absolute max this high. Therefore some sort of circuitry is needed.
jom
Posted 11/12/2012
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