大动态范围抗干扰导航接收机AGC 电路性能分析与优化设计

导航接收机的特点是信号比较微弱，通常淹没于噪声以下，其入口电平的波动几乎都由干扰引起。针对这一特点，存在干扰情况下，要求接收机的噪声系数不能显著恶化。射频通道的噪声系数是制约接收机噪声系数的因素之一，本文在给定射频通道噪声系数恶化容限的条件下，以射频通道能实现最大动态范围为优化目标，分析了动态范围及各级电路增益的求解方法；进一步，针对特殊的纯电阻网络AGC 电路，得到了更为简洁的求解方法；最后，本文给出了该类AGC 电路动态范围的设计实例并进行了测试，设计预期与测试结果得到较好的吻合。本文虽然针对导航接收机设计，但可推广应用于指导各类接收机的设计。

Analysis and Optimal Design of AGC Circuit In High Dynamic Range Anti-jamming Receivers in GNSS System

The signal power is very weak in navigation receivers, usually lower than noise. The fluctuation of the input power level is usually caused by jammers. According to this phenomenon, the noise figure of the receiver is required not to deteriorate in the presence of jammers. One of the factors in deteriorating the noise figure of the receiver is the noise figure of the RF channel. Aiming at maximizing the dynamic range of the RF channel, this paper analyzes the method of calculating the maximum dynamic range of AGC circuit and the gain of each circuit part given the bound of noise figure deterioration,and further develops a more brief method for a particular kind of AGC circuit made of resistance network. Lastly, the paper gives an example of the dynamic range design of this kind of AGC circuit, and the measured results of the example agrees well with the designing anticipation. The method in this paper can be used not only in navigation receivers, but also in various kinds of receivers.