Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would
be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate
that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views.
It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if
you would like to post something on RF Cafe's
page, please do.
Below are all of the forum threads, including all
the responses to the original posts.
Post subject: measure PA using Network Analyzer
Unread 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¬/ Any ideas?
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,
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 gain.
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