Key points of PCB design for chip decoupling or bypass capacitors

Single-point confluence solves common impedance coupling:

Figure 17: Single-point convergence solves common-impedance coupling when different power supply pins share filter capacitors

In the low-cost design, when the power supply pins of the chip share the filter capacitor of the same voltage, each power supply should be routed at a single point at the filter capacitor to avoid common impedance coupling, as shown in the figure above.

2.6.2. Different power supply pins are decoupled separately to solve the common impedance coupling:

Figure 18: Different power supply pins are decoupled separately to solve common-impedance coupling

Different power supply pins of the chip use separate high-frequency capacitors for high-frequency decoupling, while low-frequency decoupling or filtering can share filter capacitors because the effect of low-frequency parasitic inductance is negligible.

2.6.3. Separate decoupling of different power supply pins + magnetic bead isolation to solve the common impedance coupling:  

Due to the influence of the internal resistance of the power supply pins inside the chip, sometimes when the decoupling and bypass effects of high frequency are not ideal, the countermeasures of decoupling of different power supply pins and adding magnetic beads for high-frequency attenuation isolation can be used to solve the problem of common impedance coupling.