为了获得低温放大电路最佳的驻波比和噪声温度,运用级联二端口网络概念,通过矩阵变换方法,给出电压驻波比、增益和噪声系数的显式公式。为分析晶体管源极电感性网络对最佳噪声设计的影响,计算了最佳噪声信源阻抗的校正公式,用于选择合适的源极匹配网络。用上述方法设计的码分多址(CDMA)频段低温微带混合型放大器,低温(77K)实际测量得输入驻波比1.3,输出驻波比1.7,增益大于18dB,等效噪声温度不大于30K,与设计相符,证明提出的优化函数和改进的噪声模型是准确的。 In order to obtain the best VSWR and noise temperature of the low temperature amplification circuit, an explicit formula of VSWR, gain and noise figure is given by using the concept of cascaded two-port network and matrix transformation method. To analyze the influence of transistor source inductive network on the optimal noise design, the correction formula of the best noise source impedance is calculated, which is used to select the appropriate source matching network. The low temperature (77K) measurement of the input VSR 1.3, the output VSWR 1.7, the gain of more than 18dB, the equivalent noise temperature of not more than 30K , In agreement with the design, proves that the proposed optimization function and the improved noise model are accurate.