在高速PCB设计中,信号完整性问题是不可避免的。而借助于仿真工具参与PCB的设计可以极大提高产品一次成功率。本文简要阐述了信号完整性的反射、串扰及电源完整性问题,借助于Allegro PCB SI GXL、Allegro PCB PI option XL及Sig Xplore...在高速PCB设计中,信号完整性问题是不可避免的。而借助于仿真工具参与PCB的设计可以极大提高产品一次成功率。本文简要阐述了信号完整性的反射、串扰及电源完整性问题,借助于Allegro PCB SI GXL、Allegro PCB PI option XL及Sig Xplorer仿真组件对高速AD/DA系统应用实例进行了定量仿真与分析,验证了常见SI问题的正确性,提出了优化PCB设计的解决方案。展开更多
Wave reflection and transmission in a beam containing a semi-infinite crack are studied analytically based on Timoshenko beam theory., Two kinds of crack surface conditions： non-contact （open） and fully contact （c...Wave reflection and transmission in a beam containing a semi-infinite crack are studied analytically based on Timoshenko beam theory., Two kinds of crack surface conditions： non-contact （open） and fully contact （closed） cracks, are considered respectively for an isotropic beam. The analytical solution of reflection and transmission coefficients for a semi-infinite crack is obtained. The power reflection and transmission ratios depend on both the frequency and the position of the crack. Numerical results show the conservation of power transport. The transmitted energy among various wave modes is also investigated. A finite element method is used to verify the validity of the analytical results.展开更多
A study has been made on the reflected and transmitted powers generated when an arbitrarily polarized plane wave impinges at a planar interface separating an isotropic achiral medium(IAM) and an isotropic chiral mediu...A study has been made on the reflected and transmitted powers generated when an arbitrarily polarized plane wave impinges at a planar interface separating an isotropic achiral medium(IAM) and an isotropic chiral medium(ICM). It follows that the theoretical formulas are derived for the normalized reflection and transmission powers from an IAM–ICM interface for an arbitrary polarized incident wave, and those at an ICM–IAM interface for right-hand circularly polarized(RCP) or left-hand circularly polarized(LCP) incident wave are also obtained. The behavior of the reflected and transmitted waves in different cases is studied, and the dependence of the reflection/transmission of the incident wave on the incident angle and the parameters of the media is investigated in detail. Our numerical results show that high transmission is exhibited under the impedance matching condition and the incident wave can be split into two waves of the same circular polarization state in the case of the ICM–IAM interface, which indicates that circular polarizing beam splitter is achieved.展开更多
文摘在高速PCB设计中,信号完整性问题是不可避免的。而借助于仿真工具参与PCB的设计可以极大提高产品一次成功率。本文简要阐述了信号完整性的反射、串扰及电源完整性问题,借助于Allegro PCB SI GXL、Allegro PCB PI option XL及Sig Xplorer仿真组件对高速AD/DA系统应用实例进行了定量仿真与分析,验证了常见SI问题的正确性,提出了优化PCB设计的解决方案。
基金the National Natural Science Foundation of China(Nos.50478037 and 10572058)the Research Foundation for the Doctoral Program of Higher Education(No.20050287016).
文摘Wave reflection and transmission in a beam containing a semi-infinite crack are studied analytically based on Timoshenko beam theory., Two kinds of crack surface conditions： non-contact （open） and fully contact （closed） cracks, are considered respectively for an isotropic beam. The analytical solution of reflection and transmission coefficients for a semi-infinite crack is obtained. The power reflection and transmission ratios depend on both the frequency and the position of the crack. Numerical results show the conservation of power transport. The transmitted energy among various wave modes is also investigated. A finite element method is used to verify the validity of the analytical results.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61431010 and 61501350)the National Key Basic Research Program of China(Grant No.2014CB340203)
文摘A study has been made on the reflected and transmitted powers generated when an arbitrarily polarized plane wave impinges at a planar interface separating an isotropic achiral medium(IAM) and an isotropic chiral medium(ICM). It follows that the theoretical formulas are derived for the normalized reflection and transmission powers from an IAM–ICM interface for an arbitrary polarized incident wave, and those at an ICM–IAM interface for right-hand circularly polarized(RCP) or left-hand circularly polarized(LCP) incident wave are also obtained. The behavior of the reflected and transmitted waves in different cases is studied, and the dependence of the reflection/transmission of the incident wave on the incident angle and the parameters of the media is investigated in detail. Our numerical results show that high transmission is exhibited under the impedance matching condition and the incident wave can be split into two waves of the same circular polarization state in the case of the ICM–IAM interface, which indicates that circular polarizing beam splitter is achieved.
