Virtuoso Meets Maxwell: Analyzing EMX Current Density in the Virtuoso 3D Viewer

‘Virtuoso Meets Maxwell’ is a blog series that explores the Virtuoso RF and MultiTech Solutions. So how does Virtuoso meet Maxwell? This is done by combining the industry leader in custom design, Virtuoso, with powerful EM solvers that address a wide range of design needs. This series features the voices of Cadence experts who share their experience with various tools in the Virtuoso IC and Allegro Packaging world along with the nuances of RF, microwave, and high frequency designs. Watch for our posts on Mondays.

By the time you read this, Virtuoso Studio (23.1) will have been in production release for several months. If you have not had an opportunity to download this release and check out all the new capabilities, I strongly encourage you to do so. In today’s blog, I will introduce you to one of the many enhancements made to the Virtuoso RF electromagnetic flow: the ability to display current densities calculated by EM simulation in Virtuoso's 3D viewer.

EMX Planar 3D Solver has had the ability to write out current densities for some time but until now you were required to use third-party tools to view these currents. With Virtuoso Studio (23.1) and EMX 2023.1, you can now analyze these results directly in Virtuoso Studio. All you need to do is to follow a few simple steps.

First, set up the EM model as you typically would in the Virtuoso Electromagnetic Solver assistant. (For more information on building these models in the Virtuoso flow, reference the Rapid Adoption Kit link in the Related Resources section at the end of this blog.) Once you have the instances, nets, ports, and other information ready to send to EMX Solver, there are two additional steps needed to enable the saving of current density:

• On the EMX tab of the Simulation Settings form, enable the Save Currents For Single Frequency Simulations option:

• On the General tab of that same form, set up a single point frequency sweep for your frequency of interest. In this example, I am saving the current densities at 10GHz:

With these two options, the current densities will be saved when you run your EMX simulation. You can verify this in the EMX log file:

Once your simulation completes, select View 3D Mesh from the toolbar in the Electromagnetic Solver assistant:

The calculated current densities are included with the mesh, and so you will see them as part of the overall mesh structure. An assistant dedicated to current density visualization control is automatically displayed on the right side of the viewer:

Let’s explore some of the features of this viewer:

• By default, the current density heat map will be overlaid on the mesh structure. You can toggle this off and on with the Enable Current Density Display option. Once unchecked, you will see the underlying mesh.
• You can opt to see the maximum current density over all phase values or see the current density at a specific phase value.
• You can annotate arrows that will indicate the density and direction of current for a given phase.

• You can even animate the current so that it steps through all phase values with a given granularity. This will allow you to examine current crowding in specific areas of your design.

I hope that you’ve found this overview of the EMX current density visualization capability helpful, and that this blog encourages you to check out the overall Virtuoso RF solution if you have not already. The usability features of the Virtuoso EM Assistant along with the unparalleled performance and accuracy of the EMX solver will improve your electromagnetic analysis flow significantly. To learn more, reach out to your local Application Engineer.

This is the final Virtuoso RF blog of 2023, and I would like to take this opportunity to point out all the excellent blogs that our experts have written this year:

We closed out 2022 with an excellent blog by Sanam Vakili on the ability to automatically generate a package schematic from a layout:

Virtuoso Meets Maxwell: Are You Telling Me I Can Auto-Generate a Package Schematic From a Package Layout?

In March, Fadoua Gacim wrote about smart partitioning of circuits between EM and RC with her blog on excluding cells in schematic driven flows:

Virtuoso Meets Maxwell: Excluding Cells in the Schematic-Driven Flow

Claudia Roesch wrote a two-part blog on Custom Passive Device Authoring in July and August:

Custom Passive Device Authoring - Part 1 (Automatic Marker Shape Generation)

Custom Passive Device Authoring - Part 2 (LVS)

And in June we heard from Udit Kapoor who described how to use iterated instances in the analysis flow:

Virtuoso Electromagnetic Solver Assistant -Support for Iterated Instances

And finally, Kirti Sikri gave us all some valuable pointers on Allegro and Virtuoso SKILL in her blog, published in October:

Virtuoso and Allegro SKILL for Efficient Co-Design

Be sure to review any of the blogs that you may have missed. Also be sure to check out the Virtuoso RF Solution Product Page:

Virtuoso RF Solution Product Information

Happy Holidays to all, and please check back in 2024 for another great series of Virtuoso RF blogs!

Kristin Fullerton

Related Resources

• IC23.1: Virtuoso RF Solution: IC Layout Electromagnetic Simulation (Using EMX) (Rapid Adoption Kit)

For more information on Cadence circuit design products and services, visit www.cadence.com.

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About Virtuoso Meets Maxwell

The Virtuoso Meets Maxwell series includes posts about the next-generation die, package, and board design flow with a focus on reinventing and optimizing the design process to ensure that the designer remains a designer. Keep watching!

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