共查询到18条相似文献,搜索用时 187 毫秒
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天线调谐器简称“天调”是电台发射机的常用设备。其主要作用是匹配天线与发射机输出端口的阻抗,这样有利于减小由于阻抗不匹配引起的驻波反射。也就是HAM中通常所说的减小驻波比。对于固定物理尺寸的天线.尤其是谐振型天线,不可能在较宽频率范围内都自然保持良好的阻抗匹配。所以就需要天调来完成匹配工作,这样也能提高传输效率。 相似文献
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针对差分过孔引起的阻抗不连续以及过孔残桩引起的信号反射问题,通过过孔反焊盘补偿设计及端接过孔残桩减小了差分过孔及残桩引起的反射,改善了接收信号的质量。通过对比差分过孔优化设计前后的频域传输参数和时域信号眼图,说明了本方法的有效性及实用性。 相似文献
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阻抗控制与匹配问题是高速信号完整性分析中的一个重要方面。阻抗控制是保证高速信号在传播过程中波形不畸变的必要条件,而阻抗匹配是保证高速信号在接收端不发生反射,从而被正确接收的重要手段。差分线作为板级传输高速信号的有效载体,实现其阻抗控制与匹配尤为关键。利用高速器件的IBIS模型和MentorGraphics公司的仿真软件HyperLynx针对板级差分线阻抗控制与匹配的实现原理进行了仿真分析,加深了对差分线的理解和应用。 相似文献
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为了降低电路在更高速率工作时的信号反射,任意给定0~100 GHz范围内的频率点,引入LC阻抗网络,分析其适用范围并求解各给定频率点对应的LC网络,最后,在常规互连线模型的终端门电容处就近接入LC网络,使得互连线的输入阻抗与其特性阻抗相当,从而保证了信号传输路径的阻抗连续性。与阻抗匹配前比较,各给定频率点及其附近一定带宽的反射系数都有效降低,从而验证了LC网络对降低高频信号反射的正确性。基于LC网络的匹配方法同样适用于多处阻抗不连续的多层芯片结构。 相似文献
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针对声表面波器件测量中网络分析仪的负载阻抗与射频传输线特性阻抗不匹配,导致传输线上反射波幅值较大的问题,提出一种减少传输线上反射波的负载阻抗匹配系统与方案。负载阻抗匹配方案针对声表面波器件测量中输入与输出端分别设计不同的无源负载阻抗匹配网络,使输入输出端同时达到匹配状态。负载阻抗匹配系统集成了未匹配通道与匹配通道,根据负载阻抗不同调整匹配参数。对一个中心频率为101.764MHz,带宽为30MHz的声表面波器件使用该匹配方案前后中心频率处的衰减进行测量对比,实验结果表明采用该匹配方案后在中心频率点处输入及输出反射损耗分别为-49.36dB和-38.13dB,比未采用匹配方案时分别减少了44.99dB和29.44dB。 相似文献
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基于数字信号传播理论中的反射原理,采用反射系数刻画线路阻抗不匹配程度,利用线路阻抗匹配时测量得到的信道数据(直接信道、远端串扰信道和近端串扰信道),建立了一个G.fast数字用户线路阻抗不匹配时信道数学模型.当线路终端处于断开时,利用该模型生成的信道数据与实际测量的信道数据基本吻合,证明了该模型的正确性.由于采用反射系数刻画线路阻抗不匹配程度,该信道模型可仿真终端设备在不同阻抗值的情况下对通信系统信噪比的影响,从而提出线路终端设备阻抗最大允许的变化范围,为终端设备制造商在阻抗设计时提供一定的理论指导. 相似文献
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Urabe J. Fujii K. Dowaki Y. Jito Y. Matsumoto Y. Sugiura A. 《Electromagnetic Compatibility, IEEE Transactions on》2006,48(4):774-780
Almost all digital equipment has electromagnetic interference (EMI) suppression ferrite cores to encircle cables, such as mains and peripheral cables. However, their EMI suppression capability is hardly evaluated from the impedance characteristics provided by the manufacturers. Hence, this paper proposes to characterize the ferrite cores in terms of the insertion loss and the reflection coefficient. Theoretical and experimental investigations are carried out to develop a measurement jig for these parameters in the frequency range from 30 to 1000 MHz. It consists of a cylindrical metal rod placed above a metal ground plane, yielding a characteristic impedance of 270 Omega. In addition, a simple method is proposed for measuring the insertion loss and the reflection coefficient of a ferrite core under test. It is found that the proposed method can provide insertion loss data with an error of less than plusmn1.2 dB by using commercially available matching networks (baluns). The reflection coefficient of a ferrite core can be measured with an error less than plusmn1.0 dB. The matching characteristics of the adapters are critical factors that deteriorate measurement accuracy 相似文献
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Georges Roussy Nils Kongmark 《The Journal of microwave power and electromagnetic energy》2003,38(4):237-242
It is shown that a bi-directional waveguide launcher can be used advantageously for reducing the reflection coefficient mismatch of an input impedance of an applicator. In a simple bi-directional waveguide launcher, the magnetron is placed in the waveguide and generates a nominal field distribution with significant output impedance in both directions of the waveguide. If a standing wave is tolerated in the torus, which connects the launcher and the applicator, the power transfer from the magnetron to the applicator can be optimal, without using special matching devices. It is also possible to match the bi-directional launcher with two inductance stubs near the antenna of the magnetron and use them for supplying a two-input applicator without reflection. 相似文献
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本文从控制网络输入端口反射系数出发,提出了一种最小失配的宽带天线匹配网络的设计方法。利用精英保留非劣排序遗传算法分别设计了最小失配的天线无耗匹配网络和有耗匹配网络,实现网络输入端口反射系数和传输功率增益的多目标优化,并对匹配网络的传输函数对负载变化的灵敏度进行了分析。仿真实验表明,所设计的最小失配的匹配网络具有随负载变化灵敏度小的优点,证明了该方法的有效性。 相似文献
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In this letter, the impact of impedance mismatch between on-die CMOS drivers and driven transmission lines upon device reliability has been studied. The signal waveforms corrupted by the impedance mismatch, experimentally measured at the far-end of the transmission line (45 nm CMOS technology test chip), have been taken as a basis for calculations of Age parameters from the Berkeley reliability tools model. The results reveal that the impedance mismatch accelerates the device degradation due to time-dependent dielectric breakdown, negative bias temperature instability and hot carrier injection wearout mechanisms. Therefore, the impedance mismatch should be regarded also as a reliability issue. 相似文献