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基于传统AI-EBG结构,提出了一种小尺寸的增强型电磁带隙结构,实现了从0.5~9.4 GHz的宽频带-40 dB噪声抑制深度,且下截止频率减少到数百MHz,可有效抑制多层PCB板间地弹噪声。文中同时研究了EBG结构在高速电路应用时的信号完整性问题,使用差分信号方案可改善信号完整性。 相似文献
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《Microelectronics Journal》2015,46(3):258-264
Existing methods to analyze and optimize on-chip power distribution networks typically focus only on global power network modeled as a two-dimensional mesh. In practice, current is supplied to switching transistors through a local power network at the lower metal layers. The local power network is connected to a global network through a stack of vias. The effect of these vias and the resistance of the local power network are typically ignored when optimizing a power network and placing decoupling capacitors. By modeling the power distribution network as a three-dimensional mesh, the error due to ignoring via and local interconnect resistances is quantified. It is demonstrated that ignoring the local power network and vias can both underestimate (by up to 45%) or overestimate (by up to 50%) the effective resistance of a power distribution network. The error depends upon multiple parameters such as the width of local and global power lines and via resistance. A design space is also generated to indicate the valid width of local and global power lines where the target resistance is satisfied. It is shown that a wider global network can be used to obtain a narrower local network, providing additional flexibility in the physical design process since routability is an important concern at lower metal layers. At high via resistances, however, this approach causes significant increase in the width of a global power network, indicating the growing significance of local power network and vias. 相似文献
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采用"场"、"路"结合的方法研究了多层印制电路板参考平面的切换对信号完整性的影响.分析了过孔转换结构中返回电流的路径,通过"场"的方法获得两参考平面间的瞬态阻抗.将过孔转换结构等效为二端口网络,推导了基于等效电路拓扑结构的S参数与节点电压的关系,获得S参数的计算公式.计算了5 GHz内不同的过孔半径和参考面间距的回波损耗与插入损耗.结果表明:返回电流所受到的阻抗随参考平面间距的减小.而减小信号过孔的半径越小,回波损耗就越小,插入损耗越大,过孔转换结构对信号完整性的影响也越小.计算结果与全波有限元电磁仿真的结果基本吻合. 相似文献
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Sahar Pakbaten Toopkanloo Tai Boon Tan Faridah Abas Mohammad Azam Imededdine Arbi Nehdi Chin Ping Tan 《Molecules (Basel, Switzerland)》2020,25(24)
In order to improve the membrane lipophilicity and the affinity towards the environment of lipid bilayers, squalene (SQ) could be conjugated to phospholipids in the formation of liposomes. The effect of membrane composition and concentrations on the degradation of liposomes prepared via the extrusion method was investigated. Liposomes were prepared using a mixture of SQ, cholesterol (CH) and Tween80 (TW80). Based on the optimal conditions, liposome batches were prepared in the absence and presence of SQ. Their physicochemical and stability behavior were evaluated as a function of liposome constituent. From the optimization study, the liposomal formulation containing 5% (w/w) mixed soy lecithin (ML), 0.5% (w/w) SQ, 0.3% (w/w) CH and 0.75% (w/w) TW80 had optimal physicochemical properties and displayed a unilamellar structure. Liposome prepared using the optimal formulation had a low particle size (158.31 ± 2.96 nm) and acceptable %increase in the particle size (15.09% ± 3.76%) and %trolox equivalent antioxidant capacity (%TEAC) loss (35.69% ± 0.72%) against UV light treatment (280–320 nm) for 6 h. The interesting outcome of this research was the association of naturally occurring substance SQ for size reduction without the extra input of energy or mechanical procedures, and improvement of vesicle stability and antioxidant activity of ML-based liposome. This study also demonstrated that the presence of SQ in the membrane might increase the acyl chain dynamics and decrease the viscosity of the dispersion, thereby limiting long-term stability of the liposome. 相似文献
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The hollow-core photonic crystal fibers (HC-PCFs) with integrity structure have been fabricated with an improved twice stack-and-draw technique. The transmission spectrum shows that five photonic band-gaps within 450-1100 nm have been obtained.And the green fight transmission in the HC-PCFs has been observed remarkably. 相似文献