How much intermodulation distortion degradation occurs when two identical line extender amplifiers are in cascade?

When two identical line extender amplifiers are used in cascade, the intermodulation distortion (IMD) degradation behaves in a specific manner. Each amplifier contributes to the overall distortion, and when they are cascaded, the cumulative effect is not linear due to the nature of amplification and distortion interaction.

In the case of identical amplifiers, the degradation due to intermodulation distortion typically amounts to an increase of 6 decibels (dB). This stems from the fact that each amplifier adds a specific level of distortion, and the way this distortion combines when the amplifiers are cascaded results in a substantial increase, specifically a 6 dB increase. This is a well-understood outcome in RF and communications engineering, where the behavior of cascaded amplifiers can often be anticipated based on the first amplifier's characteristics alone.

The 6 dB degradation indicates that the intermodulation products are effectively doubled in terms of power level when two amplifiers are combined, leading to a significant increase in distortion that can impact signal quality. Understanding this principle is critical for maintaining signal integrity in system design involving multiple amplification stages.