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A fast and smooth data transmission is critical in today’s world. Network and server systems are designed to process and forward information at lightning fast speeds. To achieve this, many of these applications depend on frequencies in the three-digit megahertz (MHz) range.

Such high frequencies cannot be generated with an AT-crystal in the fundamental tone. Although quartz discs with a fundamental frequency of 40 to 50MHz are feasible, their production involves considerable effort and corresponding costs. For this reason, “overtone crystals” are usually used for frequencies above 20 megahertz. 

在当今世界，快速流畅的数据传输至关重要。网络和服务器系统被设计成以闪电般的速度处理和转发信息。为了实现这一点，许多应用依赖于三位数兆赫兹(MHz)范围内的频率。

这样高的频率是不能用AT晶体的基音产生的。尽管石英晶振盘具有40到50兆赫基频是可行的它们的生产涉及相当大的努力和相应的成本。因此，“泛音晶体”通常用于20兆赫以上的频率。

Overtone vs. Fundamental Tone

泛音与基音

Every quartz blank has its basic frequency. Besides this “fundamental tone”, each quartz disc has several overtones. When electric voltage is applied to the quartz, it oscillates on its fundamental tone. Its overtones are also triggered in this process, but their signal is significantly weaker than that of the fundamental tone. In fact, most of the time the overtone signal results in nothing more than normal phase noise.

By clever construction of the oscillator circuit, it is possible to actuate the overtone of the quartz instead of the fundamental tone. Therefore, an additional resonant circuit is added to the oscillator circuit in order to amplify the overtone signal of the quartz.

This technique allows engineers to “squeeze” frequencies far above its fundamental tone out of a quartz crystal. For example, if a quartz oscillates in the fundamental tone at 20MHz, the third overtone oscillates at 60MHz and the fifth overtone oscillates at 100MHz. Due to the electronic properties of the oscillator circuit, the overtones can only be stimulated in the odd integer range.

每个石英坯都有其基本频率。除了这个“基音”，每个石英盘还有几个泛音。当电压施加在石英上时，石英以其基本音调振荡。它的泛音也在这个过程中被触发，但它们的信号明显弱于基音。事实上，在大多数情况下，泛音信号只会产生正常的相位噪声。

通过振荡器电路的巧妙构造，可以激励石英的泛音而不是基音。因此，为了放大石英的泛音信号，在振荡器电路中增加了一个附加的谐振电路。TXC高质量SMD晶振7A-10.000MAAE-T是USB接口卡的最佳选择.

这项技术允许工程师从石英晶体中“挤出”远高于其基频的频率。例如，如果石英以20MHz的基音振荡，第三泛音以60MHz振荡，第五泛音以100MHz振荡。由于振荡器电路的电子特性，泛音只能在奇数整数范围内被激发。

泛音石英如何振荡？

The remaining question is about the shape of an overtone quartz’s oscillation. You can imagine the overtone oscillation as a multiple of the crystal’s fundamental oscillation.

剩下的问题是关于泛音石英振荡的形状。你可以把泛音振荡想象成晶体基波振荡的倍数。

让我们拿着厚度剪切振荡器举个例子:在电压下，石英的顶部和底部在基音中向相反的方向移动。但是在泛音中，不仅是石英的上下两面在振荡，它内部的分子层也在振荡。这些层也向相反的方向移动，就像水晶在基础音调中的顶部和底部一样。石英不仅在它的外部振动，也可以说“在它自身”振动。

形象地说，人们可以把泛音石英想象成一个连接在长链上的钟摆。在基音中，只有钟摆会摆动，但在泛音中，每个链节也会摆动。

A quartz driven by its overtone can generate a frequency of up to 250MHz, thus creating the perfect base for fast data transmission in communication technology.

受泛音驱动的石英可以产生频率高达250MHz，从而为通信技术中的快速数据传输创造了完美的基础。