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Drain current vs. Sweep output power - RF Cafe Forums
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Jeanalmira
Post subject: Drain current vs. Sweep output power Posted:
Mon Sep 19, 2005 5:06 am
General
Joined: Tue Mar
15, 2005 11:43 pm
Posts: 65
Location: Singapore
Hi all :
I have one question regarding drain current at sweep output power.
I understand that at most cases, drain current will increase as output
power increases. However, I encountered it is the other way round. The
drain current decreasing as output power increases. Why is it so?
I'm sweeping the output power in lower region than saturation
power.
and I'm sweeping dual-tone input power (for IM3 measurement).
Can anybody enlighten me?
Any advice is appreciated.
Thanks and Regards,
Jean
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Guest
Post
subject: RF Power SweepPosted: Mon Sep 19, 2005 11:50 am
The last
time I saw something like that was at lower frequencies, but the amplifier
needed neutralization - it was not very stable.
Hope this helps.
Good Luck!
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Jeanalmira
Post subject: Posted:
Mon Sep 19, 2005 8:27 pm
General
Joined: Tue Mar
15, 2005 11:43 pm
Posts: 65
Location: Singapore
Hi :
Thanks for your advice
By the way, the PA (3-stages) frequency
range is 1.8GHz, and sweep Pout is from 17dBm to 27dBm, while the estimated
P1dB >35dBm.
and the PA is unconditionally stable at this
frequency range as K>1, |S11|<1 and |S22|<1.
So I'm
not sure why the current decreasing when Pout increases?
Any
advice is appreciated.
Thanks and Regards,
Jean
Top
Guest
Post subject: Posted: Tue Sep 20, 2005 8:56
am
One possibility is that there is resistance on the bias lines.
As the power increase, the current increases, droping more voltage therefore
turning the amplifier down. Check the voltage at the input of th amplifier
to make sure that the bias voltage you think is there actually is.
Posted 11/12/2012
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