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IP3 narrowband versus wideband- RF Cafe Forums

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 Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


radiorun
Post subject: IP3 narrowband versus wideband Posted: Fri Oct 26, 2007 6:28 pm

Lieutenant


Joined: Fri Oct 26, 2007 5:29 pm
Posts: 2
I have measured the IP3 point of an amplifier with a narrowband signal.

Is there a formula which takes into account the bandwidth of the signal. Is it simply IP3 + 10 log (BWratio)?

Is there a reference which talks about this issue?


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IR
Post subject: Posted: Sat Oct 27, 2007 8:05 am

Site Admin


Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
As far as I know there is no formula that takes into consideration the BW of the signal.

According to the IEEE, the space between the 2 tones should be up to
+/-5% of the carrier or the middle frequency of operation.


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RFDave
Post subject: Posted: Sun Oct 28, 2007 8:20 pm

Captain


Joined: Sat Apr 22, 2006 11:14 pm
Posts: 10
The intercept point is defined as a combination of single tones, so there really isn't a wideband equivalent. I've read several papers about modeling wideband signals with multiple tones (Dr. Gard @ NC State has some good papers on this), so people are looking at that. In this case, you are looking at combinations of IP3/IP5/IP7, and spectral regrowth is generally what's its referred as.

If you are looking at wideband separation of tones (2 tones separated at several MHz), then the relative phasing of the 2F1-F2 and 2F2-F1 terms can lead to asymmetry on the high side and low side tones.

Dave




Posted  11/12/2012

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