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