This letter proposes a novel methodology and a metric for the assessment of the linearizability of broadband nonlinear power amplifiers (PAs). Validation of the proposed methodology and the proposed metric on two linearized Doherty PAs (DPAs) using digital predistortion (DPD) technique was carried out and it demonstrated the suitability and appropriateness of the new metric. Different from the iterative optimization procedure between the PA circuit design and the DPD algorithm compensation, the proposed method aims to provide a quantitative criterion on the PA linearizability based on its frequency-dependent amplitude modulation (AM)/AM and AM/phase modulation (PM) characteristics. To verify the effectiveness of the metric, two DPAs were characterized before and after a DPD-based linearization. The average correlation coefficients between the values of the metric and the adjacent channel power ratio after DPD were 0.8763 and 0.9156, and that between the values of the metric and the error vector magnitude after DPD were 0.8618 and 0.7200 for PA1 and PA2, respectively, indicating that the evaluation method and the linearizability metric can be used as a good measure to assess the linearizability of broadband PAs.

中文翻译：

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评估宽带非线性 Doherty 功率放大器线性化的方法和度量

这封信提出了一种用于评估宽带非线性功率放大器 (PA) 线性化的新颖方法和度量标准。对使用数字预失真 (DPD) 技术的两个线性化 Doherty PA (DPA) 所提出的方法和所提出的度量进行了验证，并证明了新度量的适用性和适当性。与 PA 电路设计和 DPD 算法补偿之间的迭代优化程序不同，所提出的方法旨在基于其频率相关的幅度调制 (AM)/AM 和 AM/相位调制 (PM ） 特征。为了验证度量的有效性，在基于 DPD 的线性化之前和之后对两个 DPA 进行了表征。