Applied Physics
Vol. 09  No. 05 ( 2019 ), Article ID: 30309 , 7 pages
10.12677/APP.2019.95029

The Characteristic of Microwave Photonic Filters Using Cascaded Two IIR Filters

Kuiying Nie, Zonghua Hu

Xingyi Normal University for Nationalities, Xingyi Guizhou

Received: May 1st, 2019; accepted: May 14th, 2019; published: May 21st, 2019

ABSTRACT

A kind of adjustable bandpass microwave photonic filters (MPFs) that can realize a high Q value is presented in the paper. It consists of two cascaded infinite impulse response filters. The theory of it was detailed analyzed, and the paper discussed the influences on the filtering performance of microwave photonic filters the coupling coefficient k1, k2, k3 of the two IIR filters, the gain of Er-doped fiber ring g, the fiber ring length L1, L2 of the two IIR filters. Theoretical calculation and simulation analysis indicate that the best filtering effect of the microwave photonic filters can be obtained when the coupling coefficient of the IIR1 filter is 0.5, the gain of Er-doped fiber ring is 2, the coupling coefficient of the IIR2 filter is k2 = 0.5 and k3 = 0.9, and the fiber ring length of the two IIR filters is equal.

Keywords:Microwave Photonic Filters, High Quality Value, Infinite Impulse Response Filters, Adjustable

1. 引言

2. 级联两个IIR滤波器的MPFs的结构和滤波原理分析

Figure 1. The structure diagram of the microwave photonic filter based on two cascaded IIR filters

Figure 2. The signal flow diagram of the microwave photonic filter based on two cascaded IIR filters

$H\left(z\right)=\left[\frac{\left(1-{k}_{1}\right)+\left(2{k}_{1}-1\right)g{z}^{-1}}{1-\left(1-{k}_{1}\right)g{z}^{-1}}\right]\left[\frac{{k}_{2}{k}_{3}{z}^{1/2}+{k}_{2}{k}_{3}\left(1-{k}_{2}\right)\left(1-{k}_{3}\right){z}^{-1/2}}{z-\left(1-{k}_{2}\right)\left(1-{k}_{3}\right)}\right]$ (1)

$H\left(\omega \right)=\left[\frac{\left(1-{k}_{1}\right){\text{e}}^{j\omega T}+\left(2{k}_{1}-1\right)g}{{\text{e}}^{j\omega T}-\left(1-{k}_{1}\right)g}\right]\left[\frac{{k}_{2}{k}_{3}{\text{e}}^{j\omega T/2}+{k}_{2}{k}_{3}\left(1-{k}_{2}\right)\left(1-{k}_{3}\right){\text{e}}^{-j\omega T/2}}{{\text{e}}^{j\omega T}-\left(1-{k}_{2}\right)\left(1-{k}_{3}\right)}\right]$ (2)

3. 仿真分析与讨论

3.1. IIR1滤波器中耦合系数对MPFs滤波性能的影响

Figure 3. The frequency characteristic of the microwave photonic filter based on two cascaded IIR filters with different coupling coefficient k1

3.2. IIR1滤波器中掺饵光纤环增益g对MPFs滤波性能的影响

Figure 4. The frequency characteristic of the microwave photonic filter based on two cascaded IIR filters with different gain of Er-doped fiber ring g

3.3. IIR2滤波器中耦合系数对MPFs滤波性能的影响

Figure 5. The frequency characteristic of the MPFs based on two cascaded IIR filters with different coupling coefficient k2

3.4. IIR2滤波器中耦合系数 ${k}_{3}$ 对MPFs滤波性能的影响

Figure 6. The frequency characteristic of the MPFs based on two cascaded IIR filters with different coupling coefficient k3

3.5. 光纤环长度L对MPFs滤波性能的影响

Figure 7. The frequency characteristic of the MPFs based on two cascaded IIR filters with different length of fiber ring L

Figure 8. Compare the frequency response of IIR1 filter and IIR2 filter with different optical fiber rings

4. 结束语

The Characteristic of Microwave Photonic Filters Using Cascaded Two IIR Filters[J]. 应用物理, 2019, 09(05): 243-249. https://doi.org/10.12677/APP.2019.95029

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