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
Mail" when a new message arrived...
All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the RF Cafe website are hereby acknowledged.
My Hobby Website:
Multitone IMD - 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: Multitone IMD Posted: Fri Oct 02, 2009 3:58
Joined: Tue Sep 04, 2007 7:54 am
This is about IM calculations
in case of multitone.
For example take an amplifier with OPI3
of 18.1dBm, gain =11 dB. Two tone IM is 58.2 dBc. Input is -19 dBm
Output = -19+11 = -8 dBm. IM = 2(18.1-(-8))+6 = 58.2dBc
I am driving this amplifier with 15 tones each having an input power
Total output power for 15 input tones
= -8 dBm.
What will be the worst case IM in dBC with respect to -8dBm
of total output power?
Post subject: Re: Multitone IMDPosted: Fri Oct 09, 2009 3:32 pm
Joined: Sun Aug 03, 2003 2:02 pm
Location: Erie, PA
The link I used
to have for a paper titled "A General Algorithm to Calculate Third Order
Intermodulation Product Locations for any Number of Tones," by Chris
Arnott, has disappeared from it's location on the CED website. So, I
just scanned in and OCRed a copy provided to me by Chris back when I
worked with him at RF Micro Devices. You can access it here:
Hopefully that will get you where you're going.
- Kirt Blattenberger
RF Cafe Progenitor & Webmaster