Crystal oscillators operate on the principle of inverse piezoelectric effect in which an alternating voltage applied across the crystal surfaces causes it to vibrate at its natural frequency. It is these vibrations which eventually get converted into oscillations.
晶体振荡器的工作原理是逆压电效应，其中施加在晶体表面的交流电压使其以固有频率振动，正是这些振动最终转化为振荡。
These oscillators are usually made of Quartz crystal, even though other substances like Rochelle salt and Tourmaline exhibit the piezoelectric effect because, quartz is inexpensive, naturally-available and mechanically-strong when compared to others.
这些振荡器通常由石英晶体制成，尽管罗谢尔盐和电气石等其他物质表现出压电效应，因为与其他物质相比，石英价格低廉、天然可用且机械强度高。
In crystal oscillators, the crystal is suitably cut and mounted between two metallic plates as shown by Figure 1a whose electrical equivalent is shown by Figure 1b. In reality, the crystal behaves like a series RLC circuit, formed by the components
在晶体振荡器中，晶体被适当切割并安装在两个金属板之间，如图1a所示，其等效电路如图1b所示。实际上，晶体的行为类似于串联RLC电路，由组件形成
- 低值电阻器 Rs
- 大值电感Ls
- 小值电容器Cs
In general, the frequency of the crystal oscillators will be fixed to be the crystal’s fundamental or characteristic frequency which will be decided by the physical size and shape of the crystal.
一般来说，晶体振荡器的频率将固定为晶体的基波或特征频率，该频率将由晶体的物理尺寸和形状决定。
However, if the crystal is non-parallel or of non-uniform thickness, then it might resonate at multiple frequencies, resulting in harmonics.
但是，如果晶体不平行或厚度不均匀，则可能会在多个频率下共振，从而产生谐波。
Further, the crystal oscillators can be tuned to either even or odd harmonic of the fundamental frequency, which are called Harmonic and Overtone Oscillators, respectively.
此外，晶体振荡器可以调谐到基频的偶次或奇次谐波，分别称为谐波和泛音振荡器。
An example of this is the case where the parallel resonance frequency of the crystal is decreased or increased by adding a capacitor or an inductor across the crystal, respectively.
例如，通过在晶体上分别增加电容器或电感器来降低或增加晶体的并联谐振频率。
The typical operating range of the crystal oscillators is from 40 KHz to 100 MHz wherein the low frequency oscillators are designed using OpAmps while the high frequency-ones are designed using the transistors (BJTs or FETs).
晶体振荡器的典型工作范围为40 KHz至100 MHz，其中低频振荡器使用运算放大器设计，而高频振荡器使用晶体管（BJT或FET）设计。
The frequency of oscillations generated by the circuit is decided by the series resonant frequency of the crystal and will be unaffected by the variations in supply voltage, transistor parameters, etc. As a result, crystal oscillators exhibit a high Q-factor with excellent frequency stability, making them most suitable for high-frequency applications.
电路产生的振荡频率由晶体的串联谐振频率决定，不受电源电压、晶体管参数等变化的影响。因此，晶体振荡器具有高Q因数和出色的频率稳定性，使其最适合高频应用。
However, care should be taken so as to drive the crystal with optimum power only. This is because, if too much power is delivered to the crystal, then the parasitic resonances might be excited in the crystal which leads to the unstable resonant frequency.
但是，应注意仅以最佳功率驱动晶体。这是因为，如果向晶体输送过多的功率，则寄生谐振可能会在晶体中被激发，从而导致谐振频率不稳定。
Further, even its output waveform might be distorted due to the degradation in its phase noise performance. Moreover, it can even result in the destruction of the device (crystal) due to overheating.
此外，甚至其输出波形也可能因其相位噪声性能下降而失真。更严重时，它甚至可能导致设备（晶体）因过热而损坏。
Crystal oscillators are compact in size and are of low cost due to which they are extensively used in electronic warfare systems, communication systems, guidance systems, microprocessors, microcontrollers, space tracking systems, measuring instruments, medical devices, computers, digital systems, instrumentation, phase-locked loop systems, modems, sensors, disk drives, marine systems, telecommunications, engine control systems, clocks, Global Positioning Systems (GPS), cable television systems, video cameras, toys, video games, radio systems, cellular phones, timers, etc.
晶体振荡器体积小巧，成本低廉，因此广泛用于电子战系统、通信系统、制导系统、微处理器、微控制器、空间跟踪系统、测量仪器、医疗设备、计算机、数字系统、仪器仪表、锁相环系统、调制解调器、传感器、磁盘驱动器、船舶系统、电信、发动机控制系统、时钟、全球定位系统 （GPS）、有线电视系统、摄像机、玩具、视频游戏、无线电系统、手机、计时器等。
