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
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IP3 out of band - 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: IP3 out of band
Unread postPosted: Mon May
30, 2005 5:56 am
What is the method to mesure and calculate
Input IP3 Out of band,
meaning 2 signal out of the IF filter caused
postPosted: Mon May 30, 2005 5:34 pm
You know, I think you need
to create your own method but what about this:
tones trough a broadband directionnal coupler,
IMDs at the output,
Divide by the gain the IMD products as measured
at the output
The ratio of what measured at the input and the
products is some sort of IMD measure.
Post subject: IP3 "out of band"
Unread postPosted: Tue May 31,
2005 11:26 am
Umm - It appears the question is poorly put.
IP3 is the (hypothetical) point where the power in the 3rd order
IM distortion products is equal to the power in the desired output.
If there is zero desired output (as there will be if your filters are
adequate), then there cannot be an IP3 as usually defined.
previous respondent hinted at this when he said that you'd get "some
sort of IMD measure" with the process he outlined.
If this measurement
is for meeting a requirement, then you need to get the specifier to
clarify the intent and execution of tests for this spec.
Thu Jun 09, 2005 9:57 pm
Jun 09, 2005 9:50 pm
I may be failing to understand
Are you talking about two out of band signals
mixing and causing an unwanted inband signal? If so, can't you inject
two tones into the part of the circuit you are concerned about?