对测控应答机中低噪声放大器(Low Noise Amplifier，LNA)和自动增益控制电路(Auto Gain Controllor，AGC)这两个重要模块进行了分析。

• The LNA and AGC are two important modules in the TT &C transponder circuit. I bring forward a method to minimize the noise figure of the whole transponder with the help of ADS.