谐振型SAW无线无源传感器的测试系统研究

Research on the Measurement System for Wireless Passive Resonant SAW Sensors

采用一种低成本、高效率的电路系统实现对谐振型无线无源声表面波(SAW)传感器的测试。该电路利用直接数字频率合成(DDS)技术产生不同频率的射频信号用以激励SAW传感器。在接收端采用功率探测器检测回波信号的包络,通过包络的变化得到待测物理化学参量的变化。该测试系统产生的激励信号功率最高可达10dBm,测试时间约为0.5s,与矢网测试结果相比,其测试相对误差仅为0.002 4%。实验结果表明,该系统能够稳定、可靠地实现谐振型SAW传感器的快速检测。

A low-cost and high efficiency circuit was used to measure the wireless passive resonant SAW sensors in this work. DDS technology was used to generate RF signals with different frequencies to excite the SAW sensor. A power detector was used in the receiving circuits to measure the envelope curves of echo signals. By analyzing the envelope, the physical or chemical parameters can be measured via this circuit. The power of the excitation signal produced by this system is up to 10 dBm and the test time is about 0.5 s while the relative error is only 0. 002 4% compared with the results from VNA. The results show that this circuit can detect the resonance frequency of SAW sensor reliability.