Tuesday, June 28, 2016
How to Solve the EMI Problem of Multi Layer PCB
There are many ways to solve the problem of EMI, modern EMI suppression method includes: using EMI inhibiting coating, the selection of appropriate EMI suppression of spare parts and EMI simulation design etc.. This paper from the most basic PCB layout of PCB layer stack in the control of radiation EMI and design skills discussion.
In IC power supply pin near arrange appropriate capacity of the capacitor, the IC output voltage jump faster. However, problems are not hereto. Due to the capacitance is limited frequency response characteristics, which makes the capacity not in the whole band generation clean driving IC output harmonic power. In addition, the transient voltage of power bus is formed in a decoupled path across the inductor will form a voltage drop, the transient voltage is the main common mode EMI interference source.
From the signal go line, good hierarchical strategy should put all the signal wire is placed in a layer or a plurality of layers. These layers next to the power layer and ground layer. For the power, good hierarchical strategy should power layer and ground layer adjacent and power layer and ground stratigraphic distances as small, this is, we talk about the "layered" strategy.
What stacking strategies help to shield and suppress the EMI following a hierarchical stacking scheme assumes that the supply current flows in a single layer, a single voltage or multi voltage distribution in the different parts of the same layer.