并发双波段射频功放数字预失真同步性研究

在并发双波段调制信号驱动下,射频功放的非线性更显著和复杂,对其进行线性化将面临新的问题。文中研究了低频波段和高频波段的同步性对线性化的影响,提出同步并发双波段射频信号生成方法,用于解决两频段信号加载时的不同步问题。文中使用1001型(中间两个载波空缺)CDMA2000信号和单载波WCDMA信号分别作为低频段和高频段的测试信号,施加到一个峰值功率为51dBm的Doherty功放上进行实验验证。实验结果表明:两频段不同步将造成无法使用数字预失真方法对功放进行线性化;在同步情况下,采用记忆多项式(MP)可显著提高并发双波段射频功放的线性度。

Synchronization Study of Digital Predistortion for Concurrent Dual Band RF Power Amplifiers

The nonlinearity of RF Power Amplifiers (RFPAs) driven by the concurrent dual band modulation signal is more complex and significant, so there are new problems for linearizing a concurrent dual band RFPA. In this paper, the in fluences of the synchronicity between the low frequency band and the high frequency band to the linearization are studied. The generation method of synchronous concurrent double band RF signals is proposed for solving the problems concerned with out of synchronization while two frequency signals are loaded. The 1001 (two carriers in the middle is empty) CDMA2000 signal and a single carrier WCDMA signal are used as low frequency and high frequency band test signal respectively, which are used to stimulate the Doherty power amplifier with the peak power of 51dBm in the experiment. The experimental results demonstrated that digital predistortion method is unefficient for linearization if the modulated signals in the two bands are not synchronized. When the signals in the two bands are synchronized, the linearity of the concurrent dual band RF power ampli fier could be improved significantly by utilizing the memory polynomial (MP) predistortion.