High speed PCB layout review checklist and PCB design inspection criteria
The circuit board assembly and circuit board processing manufacturer explained the three small criteria of high-speed PCB board layout and routing review checklist and PCB design inspection
Stack: check the stack structure and parameters. Stacking arrangement, symmetry, dielectric loss, consistency of inner layer dielectric constant.
2. Impedance: according to the current stacking conditions, whether the line width and line spacing of key signals of each layer meet the impedance requirements.
3. External interface: check whether the impedance, total length, matching length of differential pair, layout and wiring of impedance matching devices and protective devices, and ground PIN of single terminal signal connector are sufficient.
4. Analog signal: analog signal shall be routed with ground.
5. Bus interface in the board: check whether the routing topology, matching resistor placement (source and terminal matching), coupling capacitor placement, total routing length, matching of signal line and clock line lengths, and parallel routing spacing in the bus meet the 3H principle.
6. Key signals: check the high-speed clock signal (total length, matching resistance, branch topology, etc.), reset signal, control signal, interrupt signal, synchronization signal routing, and return path continuity (cross division, switching reference plane).
7. Crystal oscillator: check the layout and wiring of crystal oscillator circuit, and evaluate the impact on peripheral wiring.
8. Interlayer crosstalk: check whether the routing of adjacent signal layers will cause crosstalk, and conduct simulation analysis if necessary.
9. Power supply: plane division, power isolation (magnetic beads), through-hole flow, DC voltage drop, and placement of decoupling capacitors of key modules.
10. Timing evaluation of high-speed bus: evaluate whether the key bus establishment and holding time meet the requirements according to the wiring situation and chip manual.
Three small rules for PCB design check
1、 Check the power module. It is OK not to wrap too large a circle. The inductance and filter capacitance at the output end of DCDC should be compact, and the wiring should be thick. It is good to directly lay a large piece of copper. Pay special attention to the main power supply.
2、 Check the impedance line. Under normal conditions, all around the impedance line should be grounded.
3、 Check the network, mark the network with high frequency, high current and strong signal on the PCB with color, mark the network such as I2C serial port SPI, and then mark the audio and video signals with another color. That is to say, the network that may affect the analog signal and the analog signal network are marked at the same time, so that it is clear at a glance whether they are parallel or too close. The method of separation is to use ground wires to separate them or cross the two sides. In addition, the video signal will also affect the audio signal, so the two should also be treated in this way. It is worth mentioning that these networks should include the networks before and after the coupling capacitance, so that we can check whether the coupling capacitance is placed too far away and the signal is pulled for a long time. The circuit board assembly and circuit board processing manufacturers explained the three small criteria of high-speed PCB board layout and routing review checklist and PCB design inspection.