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Design >> RF Design >> PSS/QPSS: two tone test
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Message started by Faisal on Sep 21^st, 2007, 9:47am

Title: PSS/QPSS: two tone test
Post by Faisal on Sep 21^st, 2007, 9:47am

Hi,

I am performing a two tone test on a RF power amplifier driver. I specify two closely spaced frequencies and plot power vs frequency curve. I see intermodulation products generated at the output.

However, when I plot the power at my input port (50 ohm) i also see such intermodulation products, though of different magnitude. Am I doing something wrong in my simulation?

I am very new in RF Design, so a detailed explanation would be much helpful for me.

Kind Regards,
Fas

Title: Re: PSS/QPSS: two tone test
Post by Stefan on Sep 21^st, 2007, 11:20am

Hi Faisal,

this can either be an issue arising from a non ideal supply voltage or some sort of feedback due to the implementation of the amplifier.
It might be best if you tell us which kind of PA you implemented. And - by the way, I wouldn't care too much about something below -170 dB :)

Title: Re: PSS/QPSS: two tone test
Post by Faisal on Sep 24^th, 2007, 2:48am

Hi Stefan,

Thank you for the explanation. Yes the IM products are quite low (less than 150 dB and hence negligible). So even if I remove the amplifier and simply take a resistor across a port, i still see the IM products, but they are negligible.