How to optimize the return current of PMS (Power Measurement System) layer copper plating?

The PCB ground plane copper pour strategy of PMS directly affects signal integrity and EMC performance. Improper return current paths can increase loop area and radiation. The core of optimizing return current is to "provide the shortest and continuous mirrored return current path for each signal". First, ensure that there is a complete, unsegmented ground plane as a reference plane under critical high-speed signal lines (such as clock and PWM). If the signal needs to be layer-changed, a ground via should be placed next to the layer-changer to provide a layer-changer path for the return current. For analog circuit areas, the copper pour should be continuous, avoiding excessive segmentation by power lines or isolation slots.

If necessary, use 0Ω resistors or ferrite beads to bridge the segmented areas. The ground plane of the digital area should be as complete as possible and connected to the inner layer ground with via arrays to reduce impedance. For mixed-signal PCBs, a "unified ground plane" strategy can be adopted, where digital and analog sections share the same ground plane but are partitioned, connected only at one point below the ADC. Avoid creating isolated copper islands when pouring copper; connect them by adding ground vias. Optimized ground plane copper pours can minimize signal return current paths and loop area, thereby reducing differential-mode radiation by more than 10dB and improving signal quality.