接收机整机最小噪声系数的实现

前级LNA的性能指标的好坏对接收机整体性能起主要作用。较流行的设计方法是用ADS等仿真软件在Smith圆图上作出LNA的等增益圆和等噪声圆，以确定LNA是否同时满足所要求的增益和噪声系数指标。这种方法虽然满足了设计要求，但往往不能获得整机噪声的最佳点。本文在符合设计指标后进一步对噪声和增益的关系进行分析，建立适用于常用接收机的简单模型，在此基础上获得基于整机噪声的最佳点。这种设计方法可以广泛应用于各种微波接收系统中,降低整机哭声系数.

The Implementation of Minimal Noise Figure Receiver

The first stage of a receiver is typically a low-noise amplifier, which directly affect the global performance of the system . Popular implementation of an LNA involves drawing constant gain circles and constant noise circles with Simulation software called ADS to guarantee that both gain and noise figure requirement is met. Although the design goal is met with this method, but the best global noise performance is still not achieved. In this paper, a new simple model of common receiver is proposed after carefully examining the relationship between noise and gain of the entire circuit. A new method is proposed to find out the best global system noise performance point within the area that all meet the design target. This method can be generally applied to all kinds of RF receiver to improve the global system noise performance.