什么是晶振的频率pullability（拉伸值）？

When extra capacitance is added to the oscillator circuit, reducing the oscillator frequency. The level of tuning possible, also known as pullability, will differ from crystal to crystal as shown in Figure 3. Some manufacturers present this value in the data sheet given in ppm/pF.

晶振的频率pullability（拉伸值）指当额外的电容被添加到振荡器电路时，晶体振荡器频率降低的程度。可调谐水平，也被称为pullability（拉伸值），将不同的晶体的拉伸值也不一样，表达方式：ppm/pF。

Under normal circumstances, RF products have strict requirements for the pullability value of crystal oscillators. The pullability value is not as large as possible, or as small as possible, and the right one is the best.

一般情况下，射频类产品对晶振的拉伸值有严格的要求。晶振的频率拉伸值不是越大越好，或越小越好，合适的才是最好的。