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Design >> RF Design >> A question about IIP3 and P1dB
https://designers-guide.org/forum/YaBB.pl?num=1407388912

Message started by angel on Aug 6^th, 2014, 10:21pm

Title: A question about IIP3 and P1dB
Post by angel on Aug 6^th, 2014, 10:21pm

Generally, the IIP3 is about 10dB higher than P1dB value.

However, for the high power input, if the system has loss, (e.g., attenuator) can IIP3 is smaller than P1dB?

Could you provide the material which can explain it?

Thank you very much.

Title: Re: A question about IIP3 and P1dB
Post by aaron_do on Aug 6^th, 2014, 10:34pm

Hi,

The 10dB rule of thumb is only for "well behaved" systems where 3rd order nonlinearity dominates. Any order nonlinearity can result in gain compression, but I believe only odd order nonlinearity will result in IM3 products.

You can easily test this for yourself using any simulator...

Regarding whether IP3 can be smaller than P1dB, the answer is yes. For example, if you have both 2nd and third order nonlinearity, and one happens to cause gain expansion while the other causes gain compression, then you can probably push your P1dB higher than IP3 with the right values.

regards,
Aaron

Title: Re: A question about IIP3 and P1dB
Post by angel on Aug 7^th, 2014, 12:17am

Thank you very much Aaron, I got what you said.