Why can’t the signal line be routed under the crystal oscillator?

YXC扬兴晶振

Why can’t the signal line be routed under the crystal oscillator? [Copy link]

The main reason why signal lines cannot be routed under the crystal oscillator is to prevent signal interference and ensure the stability of the crystal oscillator. The crystal oscillator is a component based on crystal oscillation, and its performance is critical to the stability and timing of the entire system. The following are some of the main reasons to avoid signal lines under the crystal oscillator:

Electromagnetic Interference (EMI): The oscillation signal generated by the crystal oscillator is very weak and is easily affected by external electromagnetic interference. If the signal line is routed under the crystal oscillator, the signal line may act as an antenna, introducing additional electromagnetic noise and affecting the performance of the crystal oscillator.

Signal integrity: The crystal oscillator signal is a very precise clock signal, which has very high timing requirements for the entire system. If the signal line is routed under the crystal oscillator, it may cause signal distortion, clock jitter and other problems, thus affecting the stability and performance of the system.

Mutual capacitance and mutual inductance: There is mutual capacitance and mutual inductance between signal lines. If the signal lines are routed under the crystal oscillator, capacitance and inductance effects between different signal lines may be introduced, thereby affecting signal transmission and timing.

Electrical performance: Crystal oscillators usually require a very stable electrical environment to ensure the accuracy of their oscillation frequency. The presence of signal lines may introduce instability, thus affecting the performance of the crystal oscillator.

In order to ensure the performance of the crystal oscillator and the stability of the system to the greatest extent, it is usually recommended to keep the area around the crystal oscillator clear and not design the signal line to cross the bottom of the crystal oscillator. This can be achieved through reasonable layout planning and ground line design, ensuring that the electromagnetic environment around the crystal oscillator is as clean as possible, which helps to improve the reliability and performance of the system.

Since the crystal oscillator is an interference source, in principle, no wiring is allowed on all layers below the main body, especially key signal lines. It is necessary to ensure that there are no other components around the crystal oscillator to prevent mutual interference between devices and affect the quality of clocks and other signals. If the filter device is placed below the crystal oscillator, and the filter capacitor and matching resistor are not arranged according to the signal flow direction, the filtering effect of the filter will be deteriorated.

redguo

Generally, the second layer is hollowed out and GND is laid on the lower layer

fhl12431

The crystal oscillator is a point that is prone to interference. The signal line should be kept away from it as much as possible. Once coupled and superimposed with radiation, it will be more difficult to deal with.

fjdeepblue

The operating frequency of the crystal oscillator is relatively high, and it is easy to interfere with the signal line.

秦天qintian0303

Interference, interference, nothing can avoid interference