Division of digital and analog power supply planes of circuit board manufacturers
As a professional PCB manufacturer, we focus on the research and development of high-precision multilayer boards and special boards, as well as PCB proofing and production and manufacturing of SMAll and medium batch boards. How much do you know about the division of digital and analog power planes? Today, let Shenzhen circuit board manufacturers and soft Circuit board manufacturers take you to learn about the division of digital and analog power planes!
In analog digital mixed circuit, independent digital power supply and analog power supply are usually used for power supply. The PCB of analog digital mixed signal is usually divided into power planes. It should be noted that the signal line adjacent to the power supply layer cannot cross the gap between power supplies, and only the signal line on the signal layer adjacent to a large area of "ground" can cross the gap. The analog power supply can be designed in the form of PCB routing or filling rather than a power plane, so that the problem of power plane segmentation can be avoided.
An important step in PCB layout is to ensure that the power plane (and ground plane) of each component can be effectively grouped and will not overlap with other circuits. For example, in the A/D circuit, the digital power reference layer and the digital ground reference layer (digital ground plane) are usually located on one side of 1C, the analog power reference layer and the analog ground reference layer (analog ground plane) are located on the other side, and the digital stratum and the analog stratum are connected by an on resistor or ferrite magnetIC ring at a point below 1C (or at least near 1C).
If multiple independent power supplies are used and these power supplies have their own reference layers, do not allow irrelevant parts between these layers to overlap. This is because two layers of conductor surface separated by dielectric will form a capacitance. When a part of the analog power layer overlaps with a part of the digital layer, the overlapping part of the two layers forms a small capacitance. In fact, this capacitance may be very small. In any case, any capacitor can provide a path for noise from one power source to another, thus making isolation meaningless.