石英晶体负载谐振电阻测量技术研究

Load resonant resistance measurement technique research of quartz crystal

在实际应用中,石英晶体通常工作在负载谐振状态下,而这一状态下电参数的测量却一直是难点。本文对IEC标准中的计算法进行了应用研究,重点分析了π网络的分布参数对负载谐振电阻的测量结果的影响。设计了符合IEC标准的石英晶体负载谐振参数测量系统,采用DDS信号源和外差鉴相的方法,有效提高了测试精度。系统测量实验表明,石英晶体负载谐振电阻的测量误差为±10%(或±2Ω)。

Quartz crystal usually works under the resonant state, and the load resonant electrical parameters under this state are always a difficulty. This paper introduces the calculation method suggested by IEC-444 standard, and use software compensating technique instead of physical capacitance method in the measurement of resonant resistance. The paper has also introduced the test system＇s circuit designation. The new circuit imports signal resource which can produce 4 synchronized DDS channel up to 500 MSPS and new technology like Mixer/Limiter and so on. Via this way, the impact of load capacitance can be taken off greatly. The result betrayed that the value of load resonant resistance of quartz crystal is no bigger than ±10%（or±2 Ω）.