声表面波器件输入及输出负载阻抗匹配研究

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。

Research on the Input and Output Load Impedance Matching in SAW Device Measurement

In order to reduce the reflection loss of input and output in SAW device measurement due to the mismatching problem between network analyzer load impedance and RF transmission line characteristic impedance, a novel load impedance matching system and scheme is proposed. In this impedance matching scheme, two different passive load impedance networks are designed for input and output port, respectively, which can make both ports to be the matched state to reduce the reflection loss. The load impedance matching system consists of the mismatching channel and matching channel to adjust matching parameters according to the different load impedance value. The reflection loss of A SAW device with the center frequency of 101.764MHz and 30MHz bandwidth is measured in the mismatching and matching state. The experimental results illustrate that the reflection loss value of input and output is -49.36dB and -38.13dB under matching state, which are 44.99dB and 29.44dB less than that of the mismatching state.