A High-Accuracy Metric for Predicting the Power De-Rating of RF Power Amplifiers

Cubic metric (CM) is being recognized as a better alternative to determine the power de-rating of radio frequency power amplifiers (PAs) than peak-to-average power ratio (PAPR). However, in this letter our analysis shows that actually the CM is still inaccurate to predict the required PA power de-rating that satisfies the out-of-band radiation (OBR) requirement of a communication system. Further, by investigating the effect of the third-order nonlinearity of PA on the OBR, we propose a novel metric. Compared with PAPR and CM, the proposed metric has a strong correlation with the OBR, and thus it provides much higher accuracy in determining the required power de-rating of PAs, which is verified by extensive experimental results.