When I first started with PCB design, I thought a PCB designer’s job was simply to take electrical schematics and replicate them exactly as such into physical circuits. Boy, was I wrong!
Over time, and after tons of facepalm mistakes, I finally understood that this is not really what our job is.
The job of a PCB designer is actually to channel electromagnetic energy and redirect it in the most efficient way possible, following the connections as required by the electrical schematic to ensure the circuit functions properly. The goal is to keep the energy contained within the PCB and redirect it to the components or systems that need it, with as little energy as possible being converted into electromagnetic emissions.
The difference between my initial understanding and this realization is that EMI, or Electromagnetic Interference, has a huge impact on how PCBs are designed.
Unfortunately, when we first enter this field, we’re often taught that EMI is like "black magic" and totally unpredictable.
Many people start to believe that the best way to deal with EMI is to rely on last-minute filtering and shielding techniques as much as possible—using ferrite beads, capacitors, and chokes here and there—and only worry about it when we encounter issues. This turns into a situation where it's a matter of when the problem arises, not if.
The reality is, if the circuit isn’t designed with EMI in mind from the concept phase, we’re left with costly and limited options later on, once the circuit has already been developed. This often leads to a redesign of the circuit, as the right filters and shields may simply not be enough to compensate for a poor PCB layout in the first place.
Designing a PCB for low EMI requires you to consider the source, the path, and the victim of EMI.
This means that as PCB designers, our primary responsibility is to control the source of emissions. We need to think about how the circuit we design is either going to channel energy where it’s needed or convert it into unwanted emissions.
The key lies in the PCB layout itself. Unlock that, and you can free your electronic product from EMI.
I hope this helps,
Dario
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