SIwave: Everything You Need to Know About the DC IR Solver (HD)

SI Wave: Everything you need to know about the DC IR solver (HD) SI wave is a power integrity and signal integrity tool used for DC IR analysis in DCI.

This video discusses one of the power integrity solvers in SI wave, which is used when all the dies in a PCB or those you want to analyze are carrying a fixed amount of current. If one of the dies is carrying variable current, you need to do DC plus PI.

SI wave calculates the voltage drop in any power plane, voltage rise in the ground plane, current distribution, current in each via, detects overloading in any via, detects massive current accumulations, identifies the location of potential ESD issues, and many other defects.

However, SI wave should not be used to build PCBs. When importing a file in SI wave, it extracts various kinds of information, such as the stack-up, material, components, and nets. The only thing missing is assigning ports, which is necessary before starting the analysis.

Before using SI wave, it is recommended to read the electrical schematic well to save time. SI wave understands the language of nets and immediately starts looking for single nets.

A single net is an electrically connected structure without the use of any external component and could occupy many layers but cannot be electrically disconnected. To analyze a power plane, one needs to identify its nets, which could have just one net or many nets.

If there are many nets, they should be connected using resistors or inductors, which will construct what is called a passive link. SI wave treats each side of the integrated component as an independent link if discrete components exist along the path.

Therefore, it is essential to solve one net, one passive link, many passive links in a power plane, or many different power planes at once. However, one cannot solve one power plane with an integrated circuit in between.

Any process in SI wave, such as DC, PI, signal integrity, or radiation, starts by selecting a solver. Once a solver has been selected, SI wave generates a dialog box where it fills up all the information it was able to extract from the file.

For example, when clicking the DC solver, one can see the list of all the power planes, and SI wave always puts the power planes in red versus RF lines and control lines and any other kind of lines are in black. This is how SI wave distinguishes between them.

To specify the location of the source and the probe, one needs to select a passive link and specify the location of the ports in any power plane.

For example, if one knows the voltage at one point, such as the output of the VRM voltage regulator, one can specify a voltage source and set it to the desired voltage.

If one knows how much current is withdrawn by the loads, such as a CPU, one can select a current source instead of a voltage source or voltage probe.

A current source does not mean that there is a current source there, but it only means that one only knows that there is a certain amount of current going to enter that port, whether coming in or out.

Once the ports have been assigned, one can click configure simulation to populate the ports and prepare the structure for solving. Once it's done, one can validate the nets and solve the problem.

After solving the problem, one can go to the results panel and find various pieces of information, such as a plot of the currents and the voltage, voltage on the VCC, voltage of the power planes, current distribution inside the power plane, VIA density, and power distribution.

The most important information from the analysis of the DC is the VIA density, which tells you how much current is flowing in the VIAs. SI Wave can display all the VIAs and how much current is running through them. It also highlights if any VIA is carrying too much current.

The default numbers determine if the VIA will pass or fail the test, the limit. If any VIA carries too much current, the probability of a PCB failure becomes very high. Designers need to increase the number of VIAs in that area.

SI Wave can also identify sections with voltages greater than or less than certain values, find regions with current density above certain values, and find regions where power density is above certain values.

These things can be used to examine the board section by section and make sure that there is nothing, no weaknesses within it. One can also look at the voltage probes and the power distribution. The loop resistance is practically the total resistance of the main line and the return path.

The path resistance will tell you how much is the resistance on the VCC alone and how much is the resistance on the return path. SI wave allows you to export things, such as a power tree and SPICE netlist. The power tree is a flow chart that summarizes everything in one place in a graphical way.

The SPICE netlist creates a netlist SPICE model, which is useful for further analysis. After solving the problem, the first thing one would like to do is to check for refinement statistics.

The refinement statistics will tell you about the convergence and the number of iterations taken to solve the problem. The profile will give you information about the mesh used in each section and the time it took to solve the problem.

This is important to compare different models at different times to make sure that everything is being solved in the proper way.

The simulation properties will take you back to your setup, which is useful if you are reviewing the results after many months or years and are not sure how the results were produced.

In conclusion, checking the solution, displaying data in many forms, and exporting data in many forms are the things that the user of SI wave can do from doing SI wave. Of course, DCIR solution. Thank you very much for watching. I hope you enjoyed the video.

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