Pole–Zero Dynamics of High-Order Ring Resonator Filters
Pole–Zero Dynamics of High-Order Ring Resonator Filters
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DOI:
10.1109/jlt.2007.895551
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发表时间:
2007-06
影响因子:
4.7
通讯作者:
S. Darmawan;Y. Landobasa;M. Chin
中科院分区:
文献类型:
--
作者:
S. Darmawan;Y. Landobasa;M. Chin
We present a pole-zero analysis, based on the transfer matrix method, for ring resonator (RR)-based filters of Type I and Type II, consisting of mutually coupled and side-coupled RRs. The pole-zero plot determines the filter spectral characteristics and is determined primarily by the coupling coefficient between the resonators. The pole-zero dynamics (or root locus) shows how the poles and zeros move in the complex frequency plane as we vary the coupling coefficient. We show that the pole-zero dynamics for the two types of filter are complementary and, furthermore, that the pole-zero plots are related to the conditions of critical coupling and oscillation in the presence of loss or gain. We also show a pole-zero analysis for the apodization of these filters based on an actively tunable Mach-Zehnder-type coupler, where it is shown that apodization corresponds to designing pole-zero pairs with wide separations, whereas the required bandwidth determines the specific values of the coupling coefficient.