接收机下变频器噪声系数测试方法研究

Study on noise figure test method for receiver's down converter

噪声系数是影响接收机灵敏度的重要因素,但是作为接收机重要组成部分的下变频器,因其含有AGC电路(具有增益自动控制的功能)而无法采用噪声系数分析仪对此类噪声系数进行直接测量。结合工作实践,讨论了一种AGC电路噪声系数的测试方法。该方法能够消除传统增益法中测试仪器引入的影响,提高噪声系数的测量精度。

Noise figure is an important factor affecting the sensitivity of the receiver.Since the down converter,an important part of the receiver,contains AGC（automatic gain control） circuit,the noise figure analyzer cannot be used to measure the noise figure.In this paper,combining with working practice,we mainly discuss a measurement method for noise figure of AGC circuit.This method can eliminate the influence in the testing instruments in the traditional gain method,so as to improve the measurement accuracy of the noise figure.