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本文首先推导了级联着一个噪声很高的次级的参量放大器系统的有效噪声系数,并且用耦合系数和规一化负电导来表示;然后详细地讨论了这个有效噪声系数的最佳化问题。因为放大器的增益也可用耦合系数和规一化负电导来表示,因此在增益和有效噪声间获得一个单值关系式。从最佳噪声运用角度出发建立了放大器通带的上限值。最后,提出一个新的综合方法,并用数字例子作说明。
In this paper, the effective noise figure of a sub-parametric amplifier system cascaded with high noise is derived and expressed by the coupling coefficient and the normalized negative conductance. Then, the optimization of this effective noise figure is discussed in detail . Because the gain of the amplifier can also be represented by the coupling coefficient and the normalized negative conductance, a singular value relationship is obtained between the gain and the effective noise. From the perspective of optimal noise use, the upper limit of the amplifier passband is established. Finally, a new integrated approach is proposed and illustrated by numerical examples.