| Summary: | 碩士 === 中原大學 === 電子工程研究所 === 103 === This work proposes and investigates new noise reduction schemes for reducing CMN and reflection noise in a weakly coupled differential microstrip lines (WCDMLs) that crosses a weakly coupled differential embedded microstrip lines (WCDEMLs) at 45 degrees (also called a “conventional traces crossing structure”). Time- and frequency-domain analyses of the proposed schemes are performed to investigate and reduce the CMN and reflection noise by studying the differential-to-common mode conversion and the time-domain reflection (TDR) waveform using the 3-D full-wave simulator CST and HFSS. The proposed solutions reduce the peak-to-peak amplitude of the CMN in the conventional traces-crossing structure of weakly coupled differential lines, by approximately 76%~97% , while the differential impedances of the two crossing differential lines remain matched. The range of frequencies over which the magnitude of the differential-to-common mode conversions (Sc2d1, Sc4d3, Sc3d1, Sc1d3) are significantly reduced is very wide – about 0.3–16 GHz. Furthermore, the voltage drop (reflection noise) in the TDR waveform is greatly reduced using the proposed designs. Finally, a favorable comparison between the simulated results and measurements verifies the excellent CMN and reflection noise reduction performance of the proposed schemes.
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