I have some problem in prediction of 3-rd
order inter-modulation product level
. Usually, IMP3 is defined analytically for the
case that both tones are of the same level and frequency
difference between them is less than 5% of their
frequency (in-band conditions).
I have a different
case: f1 tone is of 49 dBm at 430 MHz, and f2 tone
is of 29 dBm at 549 MHz. So, they have different
levels and are spread wide.
I am interested to
predict the level of lower IMP3 (2*f1-f2) at 311
I am looking for analytical equation and
physical/mathematical explanation, which will take
in account the wide distance between tones at frequency
axes and also their difference in power levels.
Any theoretical explanation and/or links will be
I look also for translation between
measurement results taken by classical approach
and my special case.
For example, I have to understand
whether results of classical measurement of OIP3
may be applied somehow to my special case and reliably
predict "my" IMP3 at 311 MHz.