Copyright: 1996 - 2024
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while tying up your telephone line, and a nice lady's voice announced "You've Got
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My Hobby Website:
measure PA using Network Analyzer - RF Cafe Forums
RF Cafe Forums closed its virtual doors in 2012 mainly due to other social media
platforms dominating public commenting venues. RF Cafe Forums began sometime around
August of 2003 and was quite well-attended for many years. By 2010, Facebook and
Twitter were overwhelmingly dominating online personal interaction, and RF Cafe
Forums activity dropped off precipitously. If the folks at
phpBB would release a version with integrated
sign-in from the major social media platforms, I would resurrect the RF Cafe Forums,
but until then it is probably not worth the effort. Regardless, there are still
lots of great posts in the archive that ware worth looking at.
Below are the old forum threads, including responses to the original posts.
|-- Amateur Radio
Gripes & Humor
-- CAE, CAD, &
Test & Measurement
Post subject: measure PA using Network Analyzer
postPosted: Fri Jun 17, 2005 7:29 am
I want to measure AM to
AM and AM to PM using a Network Analyser. I am trying to use an external
trigger on a 8753A Network analyser. It does not seem to be triggering¬/
Unread postPosted: Fri Jun 17, 2005 8:06 am
The way to measure AM-AM and AM-PM curves is by doing Power Sweep.
You have to be extremely careful with doing these measurements, becuase
you rich to the P1dB and beyond. You have to use high power attenuator,
at the output of the PA in order to both protect the VNA input and provide
a good matching to the PA's output.
To do AM-AM, AM-PM measurements:
You have to know the output power you have to reach. Then subtract
the gain of the PA from this value. This will give the maximal input
power. Make a power sweep from a value of 10dB less to the value you
found. For example if you found that the maximal input power is +5dBm,
then the power sweep should be between -5dBm to +5dBm. A rule of thumb
is to use an output attenuator with value equal or higher to the PA's
Set the VNA's display to measure S21 phase and magnitude.
The magnitude is the AM-AM curve and the Phase is the AM-PM curve.
During the measurement you can change the bias voltage level (Vgs)
and see the effect of this on the curves.
Unread postPosted: Fri Jun 24, 2005 11:31