Dependence of power amplifier backoff on resource allocation for non-contiguous carrier aggregation

The dependence of power amplifier (PA) backoff on resource allocation for non-contiguous carrier aggregation is investigated. To be specific, assuming two non-contiguous carriers, the power spectral density (PSD) of the third-order intermodulation distortion (IM3) is approximated as a function of power allocation and PSD allocation. Based on the closed-form expression, it is proven that the PSD of IM3 is maximised when the resource allocation is inversely proportional to the PSD allocation. The PA simulations verify that such resource allocation also maximises the PA backoff.