5 Modification Suggestions for High Speed PCB Design

5 Modification Suggestions for High Speed PCB Design

After the high-speed PCB design is completed, it will generally be sent to do the board after a review. During the review process, the hardware team will generally give suggestions for modification in various aspects, such as EMC, patch, signal integrity and so on. The following summarizes some revision suggestions given by the hardware group during previous PCB reviews.

1. The multi-layer board will have at least one stratum and a complete ground plane when it is designed. However, due to the placement of components, wiring, and ground planes on the top and bottom layers, the ground plane may be divided into pieces. Some The floating copper is presented, and some are presented as a long strip of copper foil. If there is no via hole at the end of the long ground plane to return to the ground layer, this situation will be equivalent to an antenna on a high-speed circuit board, resulting in an antenna effect and serious EMC problems. Therefore, the ground planes of the top and bottom layers need to be properly handled and optimized when designing high-speed PCBs.

2. Optimize the power plane and widen the plane that can be widened as much as possible. Although some power planes seem to be very wide, there may be a few holes in the middle to block most of the copper foil. The width is actually If it becomes smaller, the impedance may become larger where the width becomes smaller, and the power supply ripple may increase. Widening the power plane has the added benefit of better board-level filtering with the ground plane. This is to optimize the PCB in terms of power integrity.

3. Some traces need to be grounded, such as clock lines. These lines should be designed to be grounded. If they are not designed to be grounded, crosstalk may occur between adjacent traces. If the digital signal lines, Then the problem of data communication error will be found. Because the rise time and fall time of the clock signal of the high-speed circuit are very fast, the adjacent lines will be induced with positive or negative pulses, which are 1 or 0 for digital signals, resulting in communication errors.

4. Some components or traces are very close to the edge of the board, which may cause problems. Because it is too close to the edge of the board, the PCB manufacturing process may damage the pads or traces.

5. Some lines can be optimized from an aesthetic point of view.