上海交通大学学报

上海交通大学学报

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超外差接收机下变频增益变化的分析与验证

  

  1. 1. 中国科学院微电子研究所，北京 100029；

    2. 中国科学院大学，北京 101408；

    3. 北京脑科学与类脑研究所，北京 102206
  • 作者简介:欧阳强生（1999—），硕士生，从事模拟与射频CMOS集成电路设计研究。
  • 基金资助:
    国家重点研发计划（2022YFF1202302）资助项目

Analysis and Verification of Down-Conversion Gain Variation in Sliding-IF Receiver

  1. 1. Institute of Microelectronics of the Chinese Academy of Sciences, Beijing 100029, China；

    2. University of Chinese Academy of Sciences, Beijing 101408, China；

    3. Chinese Institute for Brain Research, Beijing 102206, China

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摘要： 在超外差接收机中，两级本振之间的相位差会影响多个谐波的下变频增益。为了更全面地分析两级本振间的相位差对3个关键谐波的下变频增益的影响，首先，就正交和非正交两种解调方式给出了详细数学分析，并关注和分析了镜频以外频率上的干扰信号的影响。然后，基于数学分析的结果，确定了在正交和非正交解调中，两级本振的上升沿分别相差第一级本振周期的1/8和1/4时有较好的抑制干扰的效果。最后，为了验证理论分析正确性，设计了一个印刷电路板级的超外差无源混频器来完成实物测试，测试结果与理论分析一致。

关键词: 超外差接收机, 镜像频率抑制, 混频器

Abstract: In a sliding-IF receiver, the phase shift between two local oscillators (LOs) affects the down-conversion gain of multiple harmonics. This paper analyzes the impact of the phase shift between two LOs on the down-conversion gain of three key harmonics more comprehensively. Firstly, a detailed mathematical analysis is provided for both quadrature and non-quadrature demodulation methods. The impact of interference at frequencies other than the image frequency was also focused on and analyzed. Then, based on the results of the mathematical analysis, it is determined that in quadrature and non-quadrature demodulation, a shift of one-eighth and one-quarter of the period of the first LO between the two LOs’ the rising edges offers better interference suppression effects, respectively. Finally, to verify the correctness of the theoretical analysis, a printed-circuit-board-level sliding-IF passive mixer is designed. The measurement results are found to be consistent with the theoretical analysis.

Key words: sliding-IF receiver, image frequency suppression, mixer

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