SIJ had the opportunity to engage with Larry Williams, ANSYS director of technology, to find out his thoughts on how modeling and simulation needs have changed, how the industry has responded, and what’s next. At ANSYS, Larry Williams is responsible for the strategic direction of the company’s physics simulation products.  Holding a Masters and PhD from UCLA, he has over 20 years’ experience in the fields of electromagnetics and communications engineering, has delivered technical lectures internationally, and has published numerous technical papers on the subject. The following is a summary of our conversation (edited for length).

“Sometimes we must ‘break’ some design rules in order to meet requirements for size and cost.  That’s where good simulation tools are highly valuable to discover if breaking the rules are acceptable.” –Larry Williams

SIJ: How has the perception of the importance of electromagnetic simulation changed over the years?

After over 20 years in the engineering simulation business, my conclusion is that the need for advanced simulation (electrical or otherwise) is like Entropy—it always increases!  20 years ago electromagnetic simulation could solve individual components like connectors, cables, or PCB escape routing.  Every time we have delivered innovations like HPC distributed computations, layout-based FEM meshing algorithms, or automated model assembly, our users have snapped up the technology, apply it to design new systems, and then ask for even more. 

The perception of electromagnetic simulation is that it should be possible to solve complete electronic systems that include chip, package, and board while maintaining fine accuracy.  Higher frequencies for 5G, faster signaling for 100Gb/s communications, or finer voltage accuracy needed for multilevel signaling like PAM-4 all rely on detailed and reliable electromagnetic simulation.

SIJ: What are some of the biggest misconceptions about modeling EMI?

Designing for EMI compliance must be part of the entire design process, not just an afterthought in the EMI test chamber.   Most engineers know some of the design rules of EMI, such as avoiding large current loops or avoiding running high-speed traces across split power planes.  But sometimes we must “break” some design rules in order to meet requirements for size and cost.  That’s where good simulation tools are highly valuable to discover if breaking the rules are acceptable. 

We recently added an EMI scanner to our ANSYS Electronics Desktop.  That tool searches the layout to find if there are regions that break any rules.  If easily re-routed, it is generally best to alter the layout to avoid any possible EMI challenge.  Of course, full electromagnetic simulation should then be performed to ensure the compliance of the design.

Another important concept is that often an EMI problem is in actuality a signal integrity or power integrity problem.  When a signal encounters an impedance mismatch, or if devices have poor power return paths, one has to consider where energy will flow and the signal or power integrity problem induces an EMI problem.

SIJ: What are the greatest challenges your company faces technically? What steps have you taken over the last few years to improve your competitive standing?

Our industry faces several challenges to enable engineers to deliver innovative products.  Meeting that challenge is accomplished with deep technology advances in numerical methods, advanced use of high-performance computing and cloud, and automated design flows, but it goes beyond those traditions.  Our goal at ANSYS is to make engineering simulation pervasive across design function and application.  For many years, finite element analysis and other numerical methods have been leveraged by engineers for detailed component design.  Pervasive engineering simulation happens when we make detailed design bigger, faster, or more comprehensive.  It can be used in early ideation stages of design, through detailed design, all the way to deployment.

Multiphysics is a clear example of the more comprehensive simulation especially important for electronics reliability.  Our industry is being driven to add thermal and mechanical stress analysis into an otherwise electronics design flow.  ANSYS has added thermal and mechanical capabilities directly into our electronics desktop.  We also recently acquired DfR Solutions, the leader in reliable electronics simulation with their flagship tool SHERLOCK.  ANSYS has pioneered 3D Components with encryption, allowing industry players to share their component models with their customers for full system simulation while protecting the intellectual property and inner workings of their devices.  Finally, using simulation to advance your innovation is most valuable when the simulation provides highly accurate and timely results.  Some in our industry will suggest that “good enough” answers to design problems suffice.  Maybe to understand design trends or direction, but for design sign-off we adhere to unwavering accuracy in tools like ANSYS HFSS.

SIJ: How does ANSYS foster innovation in its design teams?

At ANSYS we have a very disciplined and aggressive process for innovation.  Our tools are used by our customers to drive their innovation; hence we must be all the more diligent to deliver the functionality they need.  Our process has many inputs including our customer engagements and guidance, close watch of industry trends and standards, working with industry partners, and participating in industry and academic research.   

We have both long-term and short-term roadmaps.  The long term focuses on research with innovations that are designed to anticipate industry needs.  One example is our drive to solve larger, more comprehensive simulations needed in modern electronics.  More engineers are being asked to solve tough electromagnetic problems, so we have responded by building highly automated procedures to assemble chip plus package plus board in a single environment.  This has been a multi-year effort at ANSYS.  The more we can automate, the more we eliminate setup effort so engineers can concentrate on their design challenges.

SIJ: ANSYS has always had an excellent reputation for its application engineers, can you share some secrets of how you attract, train, and retain them?

ANSYS is in an exciting business working with the most innovative companies in the world.  Our tools are essential to those companies’ development efforts and we engage in close engineering relationships.  By building some of the most consequential tools for engineering design we tend to attract some of the best talent to add to our application engineering team.  Those engineers have the pleasure of working with the very best engineers at the most innovative companies.  The efforts they make have significant impact so there is excellent job satisfaction.

SIJ: Tell us about one of your latest products for SI/PI/EMI issue simulation.

One new technology that has become very popular with our electronics customers is HFSS regions in SIwave.  SIwave is a hybrid electromagnetic solver for IC packages and printed circuit boards.  The hybrid method combines parallel plate resonances, transmission line models, radiation models, and various plane-to-plane via models to provide a comprehensive solution.  SIwave is very effective because it allows us to solve for tens of thousands of traces on multilayer structures very quickly. 

The new HFSS regions in SIwave adds a very unique functionality for accuracy with speed.  In some packages and boards there are complex arrangements of vias that are non-standard.  In those vicinities it is most accurate to carve out a region, solve using HFSS, then re-assemble into the SIwave hybrid solver.  A large PCB might have 10 or 20 such regions.  This new technology leverages the bulletproof accuracy of HFSS but the speed of SIwave enabling efficient simulation of packages and boards.

SIJ: What are the most common SI/PI simulation questions that you are hearing from your customers?

Once engineers have the fundamental training in SI/PI they become able to tackle modern design challenges in electronics.  But electronic products must also meet requirements for thermal behavior and mechanical reliability.  It used to be that electrical engineers didn’t worry about mechanical issues assuming that their mechanical design team will guarantee reliability.  That’s changing.  We hear many requests for integrated Multiphysics simulation.  This is especially true as the industry is addressing novel solutions for transportation like autonomous vehicles and transportation.  Those systems must be incredibly reliable and have a long service life.

SIJ: Can you share your product roadmap for SI/PI/EMI related products?

Of course details about our product roadmap are proprietary, but the broad perspective can be shared.  We will always work to solve bigger problems faster.  We continue to work on new numerical methods that leverage the best hardware.  The new challenges that cross physics to provide a true virtual prototype of electronics systems is an area we will continue to pursue.  Greater automation to make physics-based simulation easier to setup and solve has been a great area of effort for our development teams.  And as always, we will work in partnership with our customers to constantly refine our roadmap to meet their design challenges.