HyperLynx Helps You Turn the Traffic Light Green for Your PCB Power Delivery Network (PDN)

By Siemens Xcelerator Academy

As IC components continue to advance, the power requirements set by vendors are becoming more stringent. These requirements manifest as the board-level Power Delivery Network (PDN) impedance, which can hinder the power from reaching the ICs efficiently and on time, much like the traffic jam during rush hour.

During rush hour, a significant portion of the population is transitioning from one place to another. Does this prevent people from eventually reaching their destination? No, they will just arrive later than intended if they have not carefully planned their time.

The PDN AC behavior is analogous to that situation. When the IC transistors are switching from one state to another, the PDN needs to be well-designed to supply the IC current demand, especially the high-frequency components of the current demand. However, the PDN impedance, if high enough, will prevent the appropriate switching of the IC. Does the PDN impedance eventually prevent the high-frequency current demand from reaching the IC? No, they will just arrive later than demanded by the IC which will prevent the transistors from switching appropriately.

How to prevent that while designing your PDN? By adding local energy storage elements, the decoupling capacitors. Rather than waiting for the high-frequency current components to be supplied by the regulator, the local decoupling capacitors will discharge to provide the high-frequency current demand in time, just like turning the green traffic lights!

There’s another intrinsic capacitor that is the first component on your PDN to respond to the instantaneous current demand. This capacitor is intrinsic to the transmission plane, which brings in stackup planning as one of the critical steps in PDN design. Figure 1 illustrates how AC current demand flows through the PDN.

Figure 1- A simplified view of AC current demand

So, how do you determine the number of decoupling capacitors needed, the appropriate capacitance values, the appropriate stackup, etc.?

This is where HyperLynx decoupling analysis comes to the rescue, as it helps you design and verify your PDN AC behavior.

What about the PDN DC behavior? The PDN impedance, or resistance at DC, causes a voltage drop on the PDN copper that prevents the intended voltage at the regulator output from reaching the IC, as shown in Figure 2, which can cause component malfunction. This is usually a problem when the DC current demand is high, and the IC and the regulator are located far apart.

With HyperLynx’s advanced DC drop feature set, you can rest assured that we’ve got your back, as HyperLynx allows for a thorough analysis of your PDN’s DC drop and current.

Figure 2- Illustration of the DC drop on the PDN

To learn how to setup and perform power integrity analysis, our new course, “HyperLynx Power Integrity Analysis,” provides you with the necessary skills to design and verify the DC and AC behavior of your PDN using HyperLynx’s DC Drop and Decoupling Analysis. This will ensure that your designs meet the highest standards. As part of the learning process, you will also be introduced to behavioral models for regulators, current-demanding ICs, and decoupling capacitors, which are less time-intensive compared to SPICE models in power integrity simulations.

If you’d like to learn more about power integrity analysis in HyperLynx, you can take our new on-demand training course HyperLynx Power Integrity Analysis, available now with closed captions in 9 languages for our global audiences. This course is also offered in instructor-led format by our industry expert instructors and can be tailored to address your specific design goals. Also, you can now earn a digital badge/Level 1 certification by taking our HyperLynx Power Integrity Analysis Exam.  Your digital badge is the validation that you have acquired the necessary technical skills in the HyperLynx Power Integrity Analysis domain and can be used on LinkedIn or your email signature.

For additional questions or assistance on this topic, contact a Siemens representative at

Author: Nour Elwagdy, Customer Training Engineer, Siemens EDA Learning Services

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This article first appeared on the Siemens Digital Industries Software blog at