The voltage-biased current-voltage(I-V)characteristics of intrinsic Josephson junctions(IJJs),which are fabricated with misaligned high temperature superconducting Tl2Ba2Ca Cu2O8(Tl-2212)thin film,are investigated experimentally.Three characteristic regions in the I-V curve are observed at 47 K.In the low voltage part,the current firstly increases and then decreases slowly with increasing the biased voltage,which is shown as a bump.In the next region,the current slightly increases with increasing the biased voltage until a sudden decrease of the current appears.Thereafter,branch structure forms with increasing the voltage on the I-V characteristic.The influence of the self-heating on the I-V characteristics is investigated and the temperature dependence of the I-V characteristics is measured to explore these characteristics in detail.
WANG PeiXIE WeiHU LeiLIU XinJI LuHE MingZHANG XuZHAO XinJieYAN ShaoLin
为制作小型化线性相位高温超导滤波器,提出了一种新型开环分形谐振器,谐振器间耦合小且衰减快,可减小滤波器尺寸与不必要的寄生耦合。再者,使用相邻CQ单元共用谐振器的设计方法减少谐振器的数目进一步减小滤波器的尺寸。最后在MgO基底上设计出一个拥有三对传输零点的十阶高温超导滤波器,其带宽60%范围内群时延的波动在1 ns以内,版图大小仅有20 mm×10 mm,达到了相位均衡与小型化的目的。其边带陡峭度达到2d B/MHz,带外抑制达到40 d B,回波损耗最高为23.92 d B,插入损耗小于0.1 d B。
Intrinsic Josephson junctions in misaligned Tl2Ba2CaCu2O8 thin film were fabricated on LaAlO3 substrate. The temperature dependence of the critical current is investigated around liquid nitrogen temperature. In the current voltage characteristic, large voltage jump and lack of resistive branch are observed, which shows good consistency with the intrinsic Josephson junctions. By analyzing the large gap voltage in the curve, great suppression of the energy gap is found. Through discussing the temperature dependence of the gap voltage in liquid nitrogen temperature, it is shown that this phenomenon can be caused by the non-equilibrium quasiparticle injection. The temperature influence on the excess current also confirms the non-equilibrium effect.
利用一种新型多模谐振器设计了三通带滤波器。新提出的多模谐振器采用四模谐振器加载两个开路枝节构成,能够产生六个传输极点。该滤波器经过仿真设计后进行实物加工,测试得到各通带的中心频率分别为2.55,3.83,6.00 GHz,相对应的插入损耗分别为0.9,0.7,2.3 d B,与仿真结果吻合良好。该滤波器具有回波损耗小、尺寸小的优点,可应用到现代无线和移动通信中。
Intrinsic Josephson junctions in misaligned Tl2Ba2CaCu2O8 thin film were fabricated on LaAlO3 substrate. The temperature dependence of the critical current is investigated around liquid nitrogen temperature. In the current voltage characteristic, large voltage jump and lack of resistive branch are observed, which shows good consistency with the intrinsic Josephson junctions. By analyzing the large gap voltage in the curve, great suppression of the energy gap is found. Through discussing the temperature dependence of the gap voltage in liquid nitrogen temperature, it is shown that this phenomenon can be caused by the non-equilibrium quasiparticle injection. The temperature influence on the excess current also confirms the non-equilibrium effect.
