sivacha wrote on Nov 2nd, 2006, 8:09pm:It is iip2 only.
i am using the spectreRF and for iip2 simulation i am using the rapid IIP2 and IIP3 measurement technique.
I am able to meet the IIP3 spec but not IIP2.
When i simulated for measuring IIP3 i used swept QPSS and QPAC analyses. After reading the pdf," Rapid iip3 and iip2 measurments" i have just cross verified it. It was same.
In similar lines i measured iip2 also..
In that pdf, third harmonic was chosen as flo-(2*f1 - f2).
I chose second harmonic as flo-(f1-f2) for my IIP2.
If i am doing any mistake in this, dont hesitate to reply...
Thank you.
Choosing the 2nd harmonic as flo-(f1-f2) is not in the band of interest on the output of your mixer... so this 2nd order distortion product is not something which is causing your receiver a problem...
Previously I have designed direct conversion recievers for GSM system where i simulated ip2 by looking at the DC offset induced on the output due to a blocker signal (in GSM this is 6MHz away from the input signal) in swept qpss (pdisto).
For other systems you should be looking at f1-f2 at the output.. as it is this which again in the output band of interst for a direct conversion mixer.
In either case, ideally balanced schematic simulations will yield an unrealistically optimistic figure for IIP2... you should try a couple of runs of monte-carlo to see how that degrades (often drastically) your IP2.
In recent years there have been loads of papers by people (usually the same people like A.Pärssinen, Brandolini etc.) looking at IP2 and design/correction techniques, do a google for it.. i just did it and pasted a few links to i think useful hits. Also you should look at papers of direct conversion GSM/UMTS transceivers, they will tell you what practical design techniques are invoked in addressing IP2.
http://ieeexplore.ieee.org/iel5/9918/31527/01471166.pdfhttp://lib.tkk.fi/Diss/2006/isbn9512283670/article5.pdfhttp://ieeexplore.ieee.org/iel5/4/26570/01183846.pdfhttp://www.ieeexplore.ieee.org/iel5/8919/30323/01393163.pdf?isnumber=30323&arnum...http://bwrc.eecs.berkeley.edu/Seminars/Svelto-6.9.06/Berkeley.ppt
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how to improve IIP2 of a mixer? (Read 4967 times)