宽带单片低噪声放大器

由电路和噪声基本定义出发,导出了二端口网络的噪声相关矩阵的转移表示式和导纳表示式.并推导了两个二端口网络的级联和并联后的噪声相关矩阵.然后在此基础上得出了并联反馈放大器的噪声参数(R_n,NF_min和Y_opt)和其S参数表达式.由此设计和制造了1~7GHz两级单片低噪声放大器.在工作频率1~7GHz内,测得增益G＞20dB,带内增益波动ΔG≤±0.75dB,噪声系数NF≤2.5dB,输入输出驻波VSWR≤2.0,1分贝压缩点输出功率P_1dB≥15dBm.测试结果验证了设计的正确性.

Broad-Band Monolithic Integrated Low Noise Amplifier

The noise correlation matrixes of cascade representation,impedance representation and conductance representation of a two-port network were derived from basic circuit and noise definitions.The noise correlation matrixes of two linked two-port networks were also gotten from basic definitions.Then the noise parameters and S parameters of a parallel feedback low noise amplifier were derived using these correlation matrixes.A 1~7 GHz two-stage MMIC LNA was designed on the basis of above formulas and fabricated using 0.5μm GaAs PHEMT processes.After measurement,it is found that from frequency 1.0 GHz to 7.0 GHz,the LNA achieves a power gain of 20 dB as well as a good flatness of only ±0.75 dB,a maximum noise figure of 2.5 dB,input and output VSWRs of better than 2.0 and the output P_1dB power of 15 dBm.The design is verified by the measurement results of the MMIC LNA.