关于晶体振荡器电路Noise Immunity（抗噪声能力）解决方案，说明如下:

Noise is a common cause of oscillator failures; therefore, it’s important to know how to make the oscillator as immune to noise as possible and to know how to identify when noise is the source of the problem. One of the easiest ways to know when noise is the problem is if the oscillator malfunction appears when a big load is activated (i.e., a motor), or a power or high frequency trace is activated. A noise problem is also indicated if the problem appears when another device is turned on or when it is brought nearby, because noise could be conducted or radiated.

噪声是晶体振荡器故障的常见原因，因此，重要的是要知道如何使振荡器尽可能不受噪声的影响，以及如何识别噪声是否是问题的根源。判断噪声是否是问题的最简单方法之一是，振荡器故障是否出现在大负载（如：电机）被激活时，或者电源或高频电路被激活时。如果另一台设备开机或将其放在附近时出现噪音问题，则也表示存在噪音问题，因为噪声可能会传导或辐射。

To make the oscillator circuit more resistant to noise, make sure there’s an adequate loop gain with good margin; it is also important to check for a good amplitude level. Some microcontrollers can be configured to provide a higher amplitude output for improved noise immunity, although higher current consumption is a drawback. Other microcontrollers, especially those that implement Colpitts oscillators, have non-adjustable on-chip amplitude limitation control (ALC) loops that make increasing the amplitude level impossible.

为了使振荡器电路对噪声有更好的抵抗力，要确保有足够的环路增益和良好的裕度；同样重要的是要检查一个良好的振幅水平。一些微控制器可以配置为提供更高的幅度输出，以提高抗噪声能力，尽管较高的电流消耗是一个缺点。其它微控制器，特别是那些实现Colpitts振荡器的微控制器，具有不可调的片上振幅限制控制（Alcon）循环，使其不可能增加振幅电平。

Proper layout is also critical in attaining good noise immunity. Traces must be as short as possible. Besides adding stray elements, long traces absorb and radiate more noise since they act like antennas. Route power and high-frequency traces far from the oscillator circuit to minimize noise coupling. In some cases, it might be convenient to shield the oscillator circuit to further isolate it from noise sources. One way to accomplish this is by surrounding the circuit with a wide grounded trace. For this to work, the grounded trace must have zero current flowing through it. This is why data sheet examples use a “floating ground” with no connections other than the oscillator’s VSS. Finally, ensure adequate power supply decoupling and filtering to minimize noise in the power supply.

适当的布局对于获得良好的抗噪声能力也是至关重要的。走线必须尽可能短。除了增加杂散元素，过长的电路会吸收和辐射更多的噪音，因为其行为像天线。将电源和高频电路布置在远离振荡器电路的地方，以最大程度降低噪声耦合。在某些情况下，屏蔽振荡器电路以进一步隔离噪声源可能更方便操作。方法之一是用宽接地线环绕电路。为此，接地线必须有零电流流过。这就是为什么数据手册示例使用”浮地”（英文：“floating ground”），即：除了振荡器的VSS之外没有其它连接。最后，请确保足够的电源去耦和滤波，以尽量减少电源中的噪声。