关于无源晶振（晶体谐振器）起振电路中的等效串联电阻Rs (ESR: Equivalent Series Resistance) 与负阻Negative Resistance，晶诺威科技解释如下：

Rs or equivalent series resistance (ESR) is a parameter of the crystal, which can be found in the device specific data sheet. Negative resistance is a parameter of the complete oscillator circuit, including capacitor values, crystal parameters and on-chip circuit. To ensure correct function of the crystal oscillator, negative resistance should be at least 5 times greater than Rs.

Rs或等效串联电阻（ESR）是晶体（晶体谐振器）的一个参数，可以在对应的晶振规格书电气参数中找到。负电阻是完整的振荡器电路的一个参数，包括电容值、晶体参数和片上电路。为了确保晶体振荡器的功能正确运行，负电阻应至少为Rs的5倍。

If this is not true the oscillator might not operate as expected or it might not start up at all. The negative resistance of the circuit can be found by introducing a resistor in series with the crystal. To avoid parasitic effects it is recommended to use a 0201 resistor for this task. The threshold of resistance where the oscillator is no longer able to start up is approximately the same as the circuit negative resistance. An example of resistance vs. startup time and negative resistance threshold is shown in the figure below:

如果负电阻不够大的话，振荡器可能无法按预期运行，或者可能根本无法启动。振荡电路的负电阻值的大小可以通过引入一个与晶体串联的可调电阻（滑动电阻）来找到。为避免寄生效应，建议使用0201电阻。当振荡器不再能够启动时，此时的电阻值与电路负电阻大致相同。电阻、启动时间和负电阻的关系，如下图所示：

（Startup time vs added series resistance）

Note that higher load capacitor values decreases the negative resistance and rises the startup time.

请注意：较高的负载电容值会降低负电阻并延长晶体启动时间。