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P1dB definition - RF Cafe Forums
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ashishbondia
Post subject: P1dB definition Posted: Mon May 18, 2009
9:31 am
Captain
Joined: Wed Aug 16, 2006 8:20 am
Posts: 23
Location: India
Hi!
In the data-sheets the P1dB
for an amplifier or mixer is defined for at single frequencies. Take
the case of a UWB signal of say 500 MHz bandwidth centered at an LO
signal of 4.9 GHz where have a power distribution such that all frequencies
component from 4.65 GHz to 5.15 GHz have same amplitude level. Consider
that the amplitude levels are just below the P1dB rating at the respective
frequencies for a given amplifier.
my question is
1. Will
the device saturate?
2. If yes then how do we find the maximum power
that can be applied to the device input before it reaches saturation
in the presence of such a signal?
_________________
Ashish
Bondia,
Design Engineer- RF
Top
IR
Post subject:
Re: P1dB definitionPosted: Mon May 18, 2009 8:23 pm
Site Admin
Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location:
Germany
Hi,
P1dB by definition is frequency selective, that
means it is defined only per single frequency. If you want to know the
P1dB characterstic of your amplifier for a wide band of frequencies,
you have to measure it for each frequency.
If your BW is very
wide, you can measure the P1dB for small frequency spacings and assuming
that the device's flatness is relatively small, you can interpolate
the P1dB for the frequencies in between.
saturation occurs after
P1dB has been reached.
There is a term called back off, which
is defined as
Backoff= P1dB(in)-Pin(actual)
Where:
P1dB(in) - is the P1dB level at the input (measured).
Pin(actual)
- actual provided input power.
If the backoff which you get
is positive, then you are away from P1dB and therefore far from saturation.
_________________
Best regards,
- IR
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yendori
Post subject: Re: P1dB definitionPosted: Tue May
19, 2009 10:56 am
General
Joined: Thu Sep 25, 2003
1:19 am
Posts: 50
Location: texarcana
Is it possble to add
the tone power to LOG(N).?
N= number of channels
Posted 11/12/2012
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