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4千兆赫无线电设备用的低噪声放大器已设计成功,并投入生产。其噪声系数≤2分贝,典型增益值是10分贝,输入和输出回波损耗≥25分贝。当电源或低噪声晶体管任何一个失效时,其插入损耗通常为5～8分贝。该放大器采用了把一个砷化镓场效应晶体管与一个利用环型器的无源可靠旁路网络相连接的方法。这种方法可以使噪声系数和增益平坦度对每一个放大器都是最佳状态,而无须对输入和输出匹配进行折衷考虑。可以断定,这种单级晶体管放大器的设计与平衡放大器的设计相比,在性能和简单化方面都具有显著的优点。
Low-noise amplifiers for 4 GHz radios have been designed and put into production. Its noise figure is ≤ 2 dB, typical gain is 10 dB, input and output return loss ≥ 25 dB. Insertion loss is typically 5-8 dB when either the power supply or low noise transistor fails. The amplifier uses a method of connecting a gallium arsenide field effect transistor with a passive, reliable bypass network using a circulator. This approach allows noise figure and gain flatness for each amplifier is the best state, without having to compromise input and output matching. It can be concluded that the design of this single-stage transistor amplifier has significant advantages both in performance and simplicity over the design of a balanced amplifier.