Output Backoff (OBO)

Output backoff (OBO) is the reduction in the output power of a radio-frequency power amplifier relative to its saturated output power. It is a measure of how far below saturation the amplifier is operated in order to maintain acceptable linearity and limit nonlinear effects such as intermodulation distortion and spectral regrowth.

In satellite communications, output backoff is particularly relevant for traveling-wave tube amplifiers and solid-state power amplifiers carrying multicarrier signals or higher-order modulation schemes. Operating with increased output backoff improves signal quality and adjacent-channel interference performance, but reduces usable output power and overall power efficiency. Output backoff is closely related to input backoff, with the exact relationship determined by the amplifier’s gain characteristics.