点击查看大图此前置补偿器模块可以说明PA非线性的主要部分。如果忽略此模块的记忆性,就可以看作Hammerstein模型的无记忆非线性部分。有了记忆以后,可以用作基于记忆多项式的前置补偿器。将各项重新排列,得到式C的关系。
对各项如此重新整理就将公式简化到了有限脉冲响应(FIR)的形式,就可能以对硬件有效的LUT形式实现|x(n-i)|2多项式。多项式的方次受到自适应算法模型精度容差的限制。
对某些类型的射频PA,额外的记忆效应依赖于信号包络线。例如,这些记忆效应可以源自多种不同因素,如热和行为接近功率曲线的函数的多倍增益的电源瞬变。式1中Volterra数列的项涉及到要放大的信号与复数信号包络的向量积,可以用于构成在探索RFPA的记忆效应及如何用滤波器改进线性方面有用的关系。
作者:Hardik Gandhi
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