[USRP-users] B2x0 maximum receive power before device damage occurrs.

Marcus D. Leech mleech at ripnet.com
Thu Jul 16 13:17:16 EDT 2015


On 07/16/2015 01:10 PM, Urban Hakansson via USRP-users wrote:
> Hi,
>
> RX power -15dBm max  according to 
> http://files.ettus.com/manual/page_usrp_b200.html
>
> Why is this the max Rx Power limit? I assume this is the max RX Power 
> before device damage may occur.
>
> I looked at the schematics at 
> http://files.ettus.com/schematics/b200/b200.pdf  "B200 RF Interface", 
> page 8 of 8.
>
> Following the RF path from the RX1 (J802) SMA port to the AD9361-RX 
> here are the components I have identified, followed by the max input 
> power ratings.
>
> 1) U807: SKY13335−381LF, a pHEMT GaAs FET I/C switch that can handle 
> up to *+31 dBm*
> 2) U800:  ?
> 3) U801: SKY13317−373LF, a GaAs pHEMT single-pole, triple-throw (SP3T) 
> antenna switch that can handle up to *+30 dBm* (1 Watts) input power.
> 4) U802: BD3150L50100A00, a balanced to unbalanced transformer, that 
> can handle up to 2 Watts (*+33 dBm*)
> 5) AD9361-RX, and RFIC that can handle up to *+2.5 dBm.*
>
> When I look at the major components in the RX RF path, I cannot help 
> but think the B2x0 should be able to handle up to *+2.5 dBm*? Where 
> does the -15 dBm max RX power limit come from? (There are a bunch of 
> resistors, capacitors, and inductors in between all these components, 
> all of which I assume can handle whatever comes in.)
>
> Which component(s) in the RF path is it that will experience damage at 
> this RX power level?
>
> Thanks for your consideration,
>
> Urban Hakansson
> Senior Software Engineer
> Tecore Networks
> Phone: +1 410 872 6315
> Fax: +1 410 872 6010
> Email: uhakansson at tecore.com
>

-15dBm is specced across the entire product line where LNAs may be 
involved.  Some devices may be able to tolerate much more than that, but 
keep in
   mind the RX chains on these devices are designed to be plugged into 
an antenna system, where a -15dBm power level would be considered 
exceedingly
   loud.



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