Engineering Notes
RF POWER AMPLIFIERS TECHNICAL REFERENCE MATERIAL
Intermodulation Distortion
Second Order (IMD2) Frequencies (2 tones)
FIMD2 = F1 + F2 $ F2 - F1
Example:
F1 = 5 MHz
F2 = 8 MHz
FIMD2 = F1 + F2 = 8 + 5 = 13 MHz and
F2 - F1 = 8 - 5 = 3 MHz
Second order IMD is out of band for HPA's with a bandwidth less than one octave.

Third Order (IMD3) Frequencies (2 tones)
FIMD3 = 2F1 - F2 $ 2F2 - F1
Example:
F1 = 7 MHz
F2 = 8 MHz
FIMD3 = 2F1 - F2 = 2(7) - 8 = 14 - 8 = 6 MHz and
2F2 - F1 = 2(8) - 7 = 16 - 7 = 9 MHz
