PCB پرسرعت برطرف كردن. Here are nine rules:

Rule 1: High-speed signal routing shielding rule

در طراحی PCB با سرعت بالا ، خطوط اصلی سیگنال با سرعت بالا مانند ساعت باید محافظت شوند. اگر محافظ نباشند یا فقط تا حدی محافظت شده باشند ، نشت EMI ایجاد می شود. توصیه می شود که کابل های محافظ برای زمین گیری در هر 1000 میلی متر حفاری شود.

Rule 2: closed-loop routing rules for high-speed signals

Closed-loop routing rules for high-speed signals

What are the rules of EMI for high-speed PCB design

Closed-loop routing rules for high-speed signals

Due to the increasing density of PCB board, many PCB LAYOUT engineers are prone to make a mistake in the process of wiring. In other words, high-speed signal network such as clock signal generates closed-loop results when multi-layer PCB wiring. Such closed-loop results will generate ring antenna and increase EMI radiation intensity.

قانون 3: قوانین مسیریابی حلقه باز برای سیگنال های با سرعت بالا

Open-loop routing rules for high-speed signals

What are the rules of EMI for high-speed PCB design

Open-loop routing rules for high-speed signals

Rule 2 mentioned that the closed-loop of high-speed signals will cause EMI radiation, while the open-loop will also cause EMI radiation.

In high-speed signal network, such as clock signal, once the result of open loop is generated in the routing of multi-layer PCB, linear antenna will be generated and EMI radiation intensity will be increased.

قانون 4: قاعده پیوستگی امپدانس مشخصه برای سیگنالهای با سرعت بالا

Characteristic impedance continuity rule for high-speed signals

What are the rules of EMI for high-speed PCB design

Characteristic impedance continuity rule for high-speed signals

For high-speed signals, the continuity of characteristic impedance must be ensured when switching between layers; otherwise, EMI radiation will be increased. That is, the wiring width of the same layer must be continuous, and the wiring impedance of different layers must be continuous.

Rule 5: routing direction rules for high-speed PCB design

Characteristic impedance continuity rule for high-speed signals

What are the rules of EMI for high-speed PCB design

The cables between two adjacent layers must be routed vertically. Otherwise, crosstalk may occur and EMI radiation may increase. In short, adjacent wiring layers follow a horizontal, horizontal and vertical wiring direction, and vertical wiring can suppress crosstalk between lines.

Rule 6: Topology rules in high-speed PCB design

What are the rules of EMI for high-speed PCB design

Characteristic impedance continuity rule for high-speed signals

In high-speed PCB design, the control of circuit board characteristic impedance and the design of topological structure under multi-load directly determine the success or failure of the product.

The Daisy chain topology is shown in the figure, which is generally beneficial for a few Mhz. It is recommended to use the star symmetric structure at the back end in high-speed PCB design.

Rule 7: Resonance rule of line length

Resonance rule of line length

What are the rules of EMI for high-speed PCB design

Resonance rule of line length

بررسی کنید که آیا طول خط سیگنال و فرکانس سیگنال رزونانس را تشکیل می دهند ، یعنی زمانی که طول سیم کشی زمانهای صحیح طول موج 1/4 سیگنال است ، این سیم کشی رزونانس ایجاد می کند و رزونانس امواج الکترومغناطیسی را تابش می دهد ، تداخل ایجاد می کند.

Rule 8: Backflow path rule

قانون مسیر برگشت

What are the rules of EMI for high-speed PCB design

قانون مسیر برگشت

All high-speed signals must have a good backflow path. Minimize the backflow path of high-speed signals such as clocks. Otherwise the radiation will greatly increase, and the amount of radiation is proportional to the area surrounded by the signal path and the backflow path.

Rule 9: Device decoupling capacitor placement rules

Rules for placing decoupling capacitors of devices

What are the rules of EMI for high-speed PCB design

Rules for placing decoupling capacitors of devices

The location of the decoupling capacitor is very important. قرارگیری نادرست نمی تواند به اثر جداسازی برسد. اصل این است: نزدیک به پین ​​منبع تغذیه ، و سیم کشی منبع تغذیه خازن و زمین توسط کوچکترین منطقه احاطه شده است.