I. Introduction
Due to the fact that microwave electronic systems are very precise signal receiving systems, the noise of the system itself often has a significant impact on the overall performance of the system [1]–[11]. Therefore, optimizing the signal-to-noise ratio (SNR) of the entire system has always been a direction of effort for designers. The calculation of SNR is shown in (1), where Ps is the power of the input signal and Pn is the power of the noise signal. \begin{equation*}SNR = 10\log \frac{{{P_s}}}{{{P_n}}}\tag{1}\end{equation*}