Many PCB cards are no longer single-function circuits (digital or analog circuits), but rather a mixture of digital and analog circuits. Therefore, it is necessary to consider the mutual interference between them when Reverse Engineering PCB Card Digital Circuits & Analog Circuits, especially the noise interference on the ground.
The frequency of the digital circuit is high, and the sensitivity of the analog circuit is strong. For the signal line, the high-frequency signal line is as far as possible away from the sensitive analog circuit device. For the ground line, the whole human PCB card has only one node to the outside.
The number of processing and the common ground must be handled inside when Reverse Engineering PCB Card Digital Circuits & Analog Circuits, and the digital ground and the analog ground inside the pcb cards are actually separated from each other, but only at the interface where the PCB is connected to the outside (such as a plug). The digital ground is slightly shorted to the analog ground. Please note that there is only one connection point. There is also no common ground on the PCB, which is determined by the system design.
The signal line is placed on the electrical (ground) layer, In the wiring of multi-layer PCB Cards, since there are not many lines left in the signal line layer, the addition of layers will cause waste and increase the workload for production, and the cost will increase accordingly. To resolve this contradiction, consider wiring on the electrical (ground) layer. The power layer should be considered first, followed by the ground layer. Because it is best to preserve the integrity of the formation.