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The Effect of Power Distribution Network (PDN) Elements On Impedance

Concepts of Power Integrity: The Effect of PDN Elements On Impedance
In this paper, we continue our discussion of the power distribution network or PDN. As discussed in the paper ‘Concepts of Power Integrity: Controlling Impedance across a Bare Cavity,’ a low-impedance PDN is critical for maintaining adequate current delivery to the receiver and, ultimately, for ensuring the proper performance of a printed circuit board (PCB).

The examples in this paper shows how the addition of cavity elements, such as a voltage regulator module (VRM), decoupling capacitors, and stitching vias, influence the impedance of a cavity.

Different ways to lower the PDN impedance profile of the cavity

  • The addition of a VRM, decoupling capacitors, and stitching vias lowered the impedance profile of the cavity at different frequency ranges

  • Decreasing the thickness of the cavity further lowered its impedance, to the extent that the impedance of a thin cavity was not affected by the location of a capacitor.

  • It is very important to make the PDN cavity as transparent as possible for signals' return paths.

Learn more HyperLynx PDN Optimization Analysis

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