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AD9361/4 IIP3 measurement

Question asked by sotonzi on Apr 9, 2015
Latest reply on Apr 13, 2015 by mhennerich

Hi everyone,

 

I am measuring the AD9364 Rx IIP3 by generating two tones (ie 1MHz spacing) on each side of the rx centre frequency. The measured IIP3  is -30dBm ish, which is far more less than the IIP3 values in the spreadsheet. I am using the maximum rx gain for each carrier frequency (ie 74.5dB for 800MHz, and 65.5dB for 5500MHz according to the spread sheet). The input power I used are slightly different for each carrier frequency, which I tried to use a maximum power.

 

By looking at the ad936x IIP3 measurement documentation, I found my measured IIP3 is close to the in-band IIP3. Can the experts tell me whether my assumption is right or not?

 

When measuring the IIP3, when I alter the input signal power (ie increase by 10dB), I can see the signal power increase around 10dB, the 3rd order production also increase however less than 30dB as expected. That seems wrong to me? Is my setting wrong?

 

Again, when I set the rx gain for the receiver, if I set the rx frequency first, the software only allow me to use a limited gain (for example set frequency at 5500GHz at gain 62dB). However if I set the gain first and then the rx frequency, it doesn't complain, for example I can set gain at 77dB at frequency of 5500GHz. I am using the analog devices NO-OS software.

 

Is above description clear? Can anyone help me?

 

Thanks,

Zifnag

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