定向耦合器反馈型短波低噪声高线性放大器设计

Design of a short-wave amplifier with high linearity and low noise based on directional coupler feedback

利用双极性晶体管采用定向耦合器负反馈的形式设计了一款适用于短波超宽带接收机的低噪声高线性放大器。负反馈技术拓展了动态范围以及增益平坦度，定向耦合器的低损耗以及隔离吸收对噪声和输入输出端的匹配有很大改善。该放大器射频应用频率是1.5～100MHz，覆盖了6个倍频程。测试结果表明：放大器增益13dBm，噪声低于2.7dB，输出三阶截点高于43dBm，1dB压缩点高于26dBm,，输出二阶截点高于80dBm。

A short-wave ultra-wideband amplifier with high linearity and lower noise based on coupler negative feedback is presented, which is used for shore-wave ultra-wideband receiver. Negative feedback technology expands the dynamic range and gain flatness, low loss and isolation of the directional coupler greatly improve on the noise and input-output matching. The amplifier has RF frequency of 1.5 to 100MHz, covers 6 octaves. The test results show that the amplifier has been designed with a gain of about 13dBm, gain flatness of 0.1 dB, maximum noise figure of 2.7 dB, referred 1-dB compression point （P1dB） of above 26 dBm, output of third order intercept point of higher than 43 dBm and output of second order intercept point of higher than 80 dBm.