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KCC's Quizzes: AQQ229 about IP3 lab measurement


IP3 (intercept point of order 3) is a spec one find in many RF component datasheet. It is directly linked with the linearity of a function behavior. 

More precisely, It indicates the amount of the intermodulation products of order 3 that interfere with the baseband.

The above pictures show the lab setup and a Spectrum Analyzer screenshot to measure the IP3 of a device (DUT) in the lab.


  1. What are the frequencies provided by sources 1 and 2?
  2. What is the IP3 measured in that test?

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[edited by: emassa at 5:46 PM (GMT -5) on 2 Mar 2023]
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  • 1) Fundamental Freqs    f1= 1245 MHz, f2= 1255MHz

    2f1-f2= 1235 MHz,  2f2-f1= 1265 MHz 

    2) Delta -11dBm - (-45dBm) = 34dB = 2*(OIP3 - Pout) = 2 ( OIP3 - (-11dB) ) -- > OIP3 = 6dBm

    I believe this was a 7dB Gain device (forgotten to be mentioned in the text :-) )  Then IIP3= 6-7 = -1dBm 

       you find OIP3, not IIP3. Without OP-Gain info, we cant calculate IIP3 ;-)  

    Edit: Added IM3 Frequencies 2f2-f1 and 2f1-f2 Frequencies. 

  • Thanks Hakan for your answers and your remark about OIP3! Without telling too much detail here, I can say "big applause"! 

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