Compared to superheterodyne receiving circuits, the Zero - IF receiving circuits is featured by simple structure, in- tegration accessibility to miniaturization and no image frequency interference, which saves the image frequency suppression filter with both high cost and low integration accessibility. The signal channel in Zero - IF receiving circuit can be set in low frequency and only a low - pass filter is thus needed. However, the native defects in Zero - IF receiving circuits, such as DC drift, LO leak- age and LF noise, lead to constant failures in achieving the Zero - IF. Therefore, by analysing these defects, two principal im- provements are made in the design of a certain 915MHz mobile communication terminal receiving circuits, based on which the sim- ulation design is completed and its feasibility and rationality have been theoretically verified through simulation seftwares ADIsimRF and ADS.%与超外差接收电路相比，零中频接收电路结构简单，易于集成实现小型化，无镜频干扰，能省去昂贵且难以集成的镜频抑制滤波器，信道选择在低频进行，只需使用低通滤波器。但直流漂移、本振泄漏、低频噪声这些零中频结构固有的缺陷却使人们实现零中频的尝试不断失败。本文在某915MHz频段移动通信终端接收电路设计中，通过对这些缺陷的分析，提出对零中频结构的两处改进措施，用以抑制直流漂移、本振泄漏和低频噪声，完成了915MHz零中频移动通信终端接收机的仿真设计。通过仿真软件ADIsimRF和ADS的计算与仿真，理论上验证了其可行性和科学性。
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