When a signal is amplified, the RF Power amplifier (PA) creates distortion due to the non linearity of the different components used in the PA. The first type of distortion generated by a PA is called harmonics which a multiple of the carrier frequency. For example, if a user’s carrier is at 1 GHz then 2nd harmonic will be at 2 GHz, 3rd harmonic at 3 GHz and so on. Harmonics can easily be reduced by adding a filter at the output of the PA. The second type of distortion is called Inter Modulation Distortion product (IMD) which is generated when multi carriers are amplified. IMD are unwanted products in close proximity to the carriers and so cannot be filtered. To reduce the level of IMDs either users decrease the output power of the PA (Back-Off) or they add a correction system.