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概述在典型的4～8千兆赫倍频程带宽低噪声放大器中,目前主要采用隧道二极管、参量放大器以及行波管。但此三者各有其不足之处。隧道二极管噪声系数可以做得很低,但仅能处理低电平信号,于-20分贝毫瓦处便饱和;参量放大器噪声系数最低,但成本高,而且在倍频带宽应用时产生相当的畸变;行波管应用较广,一般具有低噪声放大器的大部分优点,如噪声低,信号处理能力强等,但遗憾的是行波管体积大,比如典型的
Overview In the typical 4 ~ 8 gigahertz octave bandwidth low noise amplifier, the main use of the tunnel diode, parametric amplifier and traveling wave tube. However, each of these three has its own shortcomings. The tunnel diode noise figure can be very low, but can only handle low-level signals, saturating at -20 dB milliwatts; the parametric amplifier has the lowest noise figure, but at a high cost, with considerable distortion in octave bandwidth applications ; Traveling wave tube is widely used and generally has most of the advantages of low noise amplifier such as low noise and strong signal processing capability. Unfortunately, traveling wave tubes have large volume, such as typical