OIP3 and spectral re growth on RF amplifier

any idea how to relate OIP3 with the amount of expected spectral re growth? Typically the higher OIP3, the lower out of band power would be my take. However, I surfed through the net without finding much accurate info about this.

Any comments are welcomed.

Cheers

Spectrum regrowth (or ACPR) is direct related to IM products, especially IM3 and IM5.
At high output power IM3 tones are function of IM5 (5th degree and higher) nonlinearities, when IM5 is not affected by IM3.
For example an empirical percent contribution for ACPR1 at high output power is about 80% IM3 and 20% IM5.
At low output power the 5th order IM5 can be neglected, and the amplitude of the IM3 which is proportional to OIP3 are the only dominant factor for spectrum regrowth.
OIP3 = Pout(dBm) + IM3(dBc) / 2
OIP5 = Pout(dBm) + IM5(dBc) / 4