为了分析射频直接采样系统中的等效相位噪声模型,文中给出了射频直接采样接收机的简化构架,然后理论推导了射频直接采样接收机采样输出信噪比与采样时钟之间的关系表达式。最后,通过建立仿真实验平台对推导结论进行了实验验证,结果表明:射频直接采样系统对采样时钟的频谱纯度要求高,采样输出的信噪比和无杂散动态范围会在时钟信号频谱的基础上恶化。射频直接采样系统可视为射频本振混频和量化采样的过程,其等效相位噪声模型与常规超外差式接收机是一致的。

In order to analyse the equivalent phase noise model for the RF direct sampling system, a frame of RF direct sampling receiver is presented and the expression is deduced between the SNR of RF sampling output and sampling clock theoretically. Atlast, experiment is validatd by simulation experiment unit result, indicates that RF direct sampling system needs high spectrum quality, and its SNR and sprious free dynamic raage (SFDR) of sampling signal is deteriorated based on sampling clock spectrum. RF direct sampling system is close to the process of mixing and sampling, and its equivalent phase noise model is coherent with general IF receiver.