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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。
Driven by the concurrent dual-band modulated signal, the nonlinearity of the RF power amplifier is more significant and complicated. The linearization of the RF power amplifier will face new problems. In this paper, the influence of the synchronization of the low-frequency band and the high-frequency band on the linearization is studied. A method of simultaneous generation of dual-band RF signals is proposed to solve the problem of unsynchronization when the two-band signals are loaded. In this paper, 1001 CDMA2000 signals and two single-carrier WCDMA signals are used as the test signals in the low-frequency band and the high-frequency band, respectively, and applied to a Doherty power amplifier with a peak power of 51 dBm for verification. The experimental results show that the two bands can not be linearized by using digital predistortion method when they are out of synchronization. Using the memory polynomial (MP) can significantly improve the linearity of the dual-band RF amplifier.