设计了一款4位MEMS开关线式移相器,由SP4TMEMS开关和微带传输线构成,工作于X波段。单刀四掷(single pole 4throw,SP4T)开关用于切换两条不同电长度的信号通道,即参考相位通道和延迟相位通道。每个SP4T开关包含4个悬臂梁接触式RF MEMS串...设计了一款4位MEMS开关线式移相器,由SP4TMEMS开关和微带传输线构成,工作于X波段。单刀四掷(single pole 4throw,SP4T)开关用于切换两条不同电长度的信号通道,即参考相位通道和延迟相位通道。每个SP4T开关包含4个悬臂梁接触式RF MEMS串联开关。介绍了4位MEMS开关线式移相器的总体设计,并给出了其关键部件SP4T开关和相位延迟线的设计细节。采用ADS软件仿真分析了器件的电气性能。仿真分析得到:SP4T开关在中心频率10GHz处的回波损耗为-36dB,插入损耗约为0.18dB;移相器各相位的回波损耗均低于-15dB,插入损耗为-0.8～-0.4dB。这种射频MEMS移相器具有小型化、低功耗和高隔离度的优点。展开更多
Secretion systems, macromolecules to pass which can mediate the across cellular membranes, are essential for virulent and genetic material exchange among bacterial species[1]. Type IV secretion system （T4SS） is one ...Secretion systems, macromolecules to pass which can mediate the across cellular membranes, are essential for virulent and genetic material exchange among bacterial species[1]. Type IV secretion system （T4SS） is one of the secretion systems and it usually consists of 12 genes： VirB1, VirB2 ...VirB11, and VirD4[2]. The structure and molecular mechanisms of these genes have been well analyzed in Gram-negative strains[3] and Gram-positive strains were once believed to be lack of T4SS. However, some recent studies revealed that one or more virB/D genes also exist in some kinds of Gram-positive bacteria and play similar role, and form a T4SS-like system[3]. The VirBl-like, VirB4, VirB6, and VirD4 genes were identified in the chromosome of Gram-positive bacterium Streptococcus suis in our previous studies and their role as important mobile elements for horizontal transfer to recipients in an 89 K pathogenicity island （PAl） was demonstrated[45]. However, their structure and molecular mechanisms in other strains, especially in Gram-positive strains, are remained unclear.展开更多
文章基于赝高电子迁移率晶体管(Pseudomorphic High Electron Mobility Transistor,PHEMT)工艺,设计一款Ka波段单刀四掷反射式开关芯片。为降低芯片插入损耗和提高隔离度,电路选取并联型反射式拓扑结构。同时,为提高工作带宽和减小芯片...文章基于赝高电子迁移率晶体管(Pseudomorphic High Electron Mobility Transistor,PHEMT)工艺,设计一款Ka波段单刀四掷反射式开关芯片。为降低芯片插入损耗和提高隔离度,电路选取并联型反射式拓扑结构。同时,为提高工作带宽和减小芯片面积,采用高低阻抗变换线替代50Ω传输线方式匹配阻抗。芯片采用0 V和-5 V电压控制支路开关的导通或关断。芯片尺寸为1.85 mm×1.55 mm。实测结果表明,在28~42 GHz工作频带范围内,输入输出回波损耗小于-10 dB,插入损耗小于3.2 dB,隔离度大于38 dB,实现了开关芯片低插损、高隔离度的优异性能。展开更多
文摘设计了一款4位MEMS开关线式移相器,由SP4TMEMS开关和微带传输线构成,工作于X波段。单刀四掷(single pole 4throw,SP4T)开关用于切换两条不同电长度的信号通道,即参考相位通道和延迟相位通道。每个SP4T开关包含4个悬臂梁接触式RF MEMS串联开关。介绍了4位MEMS开关线式移相器的总体设计,并给出了其关键部件SP4T开关和相位延迟线的设计细节。采用ADS软件仿真分析了器件的电气性能。仿真分析得到:SP4T开关在中心频率10GHz处的回波损耗为-36dB,插入损耗约为0.18dB;移相器各相位的回波损耗均低于-15dB,插入损耗为-0.8～-0.4dB。这种射频MEMS移相器具有小型化、低功耗和高隔离度的优点。
基金supported by the National Natural Science Foundation of China (No. 81201322)the Priority Project on Infectious Disease Control and Prevention 2011ZX10004-001 and 2013ZX10003006-002 by the Chinese Ministry of Science and Technology and the Chinese Ministry of Healththe Foundation of State Key Laboratory for Infectious Disease Prevention and Control (Grand No. 2011SKLID303)
文摘Secretion systems, macromolecules to pass which can mediate the across cellular membranes, are essential for virulent and genetic material exchange among bacterial species[1]. Type IV secretion system （T4SS） is one of the secretion systems and it usually consists of 12 genes： VirB1, VirB2 ...VirB11, and VirD4[2]. The structure and molecular mechanisms of these genes have been well analyzed in Gram-negative strains[3] and Gram-positive strains were once believed to be lack of T4SS. However, some recent studies revealed that one or more virB/D genes also exist in some kinds of Gram-positive bacteria and play similar role, and form a T4SS-like system[3]. The VirBl-like, VirB4, VirB6, and VirD4 genes were identified in the chromosome of Gram-positive bacterium Streptococcus suis in our previous studies and their role as important mobile elements for horizontal transfer to recipients in an 89 K pathogenicity island （PAl） was demonstrated[45]. However, their structure and molecular mechanisms in other strains, especially in Gram-positive strains, are remained unclear.
