How EMC simulation is helpful for IC application Reference board designs | Part 1 of 2

 by Joe Sivaswamy, Updated on December 9, 2022

When a semiconductor company introduces a new IC to the market, in addition to presenting technical data and other marketing material, they also offer a reference design to attract potential customers.

The reference design is provided in the form of an evaluation board. It is a proof-of-concept platform to target customers with relevant information; Information that can be used in their future designs or to upgrade their present designs. The reference design is generally targeted for specific applications. Yet the IC can be used in a broader market segment. The aim is to increase the likelihood of the IC being taken into consideration in customer designs. This is to help the manufacturer gain a competitive advantage.

The reference design helps customers to validate the IC’s performance. To ensure that the IC meets certain critical parameters of their product design.

Using Reference design board for EMC performance
It is also common practice for IC manufacturers to use the same reference design to demonstrate EMC compliance of the IC. EMC compliance is demonstrated for the targeted market by providing EMC measurement data. This EMC measurement data is important to customers when using power converters and sensors in their end products. Power converters are generally the potential emission sources, while sensors are susceptible to external emission.

EMC Simulations for reference design boards
EMC simulation can help semiconductor manufacturers in two ways. It is useful in the design of reference design boards as well as addressing end-use IC applications’ EMC compliance.

•     For reference board design – pre and post-PCB design
While designing reference boards, not only should the ICs meet the EMC requirements, but the PCB too must be designed for compliance with the EMC standards.

•     Pre-PCB fabrication simulation
An EMC simulation can be run on the board design before it goes to fabrication. Application engineers designing the reference design boards will have access to the PCB files (schematics, ODB++, BOM, etc..). They can import these design files into the simulation software. IC noise source model can be generated through transient simulation (in Spice simulation), or importing/generating through models features within the simulation tools.

i) PCB transfer function: EMC simulation allows characterization of the noise source (the IC) and the emission path (the PCB, cables etc.) separately. The designer can determine how the PCB transfer function influences the emission results. The designer can thus design the PCB before fabrication to reduce resonances that influence the emission results.

Figure 1. A CISPR25 test setup against the setup equivalent circuit. The simulation can help to analyze the transfer function (of the PCB) and the noise source separately.
(Example from Simyog compliance Scope)

ii) Importing / generating equivalent noise source: Most IC companies offer only encrypted spice files to its end users. Whereas, they have access to unencrypted models. These models can be used for more accurate circuit simulation to derive the IC noise source for the simulation.

The simulation helps to get the PCB qualified for compliance to specific EMC standards before fabrication.

•     Simulation post PCB fabrication and assembly
After the PCB gets ready and fabricated, it is also possible to make actual measured noise levels on specific IC pins. This data can be imported as a noise source into the EMC simulation to rerun the simulation. This can help to improve the noise source model for the simulation.

On measurement completion, the simulation results can be correlated to the measurement results. Both measurement and the simulation results can be provided to customers to assist in their end use applications.

Figure 2. Correlation: Measurement Vs Simulation for Richtek RT2875B test PCB

In Part 2 of this blog series, we shall discuss how EMC simulation for reference design board is useful in application support to end users.

Simulation tool designed for EMC test engineer

 by Joe Sivaswamy, Updated on November 26, 2022

Computational electromagnetic simulation tools have been in use for more than a decade. Yet, hardware design engineers have not been able to use them effectively.

Reasons for the limited use of simulation tools for EMC testing

In most cases, engineers involved in EMC compliance testing hesitate to use EMC simulation tools. This is due to a lack of EM solver knowledge. In general, EM Simulation engineers that work on signal and power-integrity analysis, employ simulation tools for EMC analysis. They generally don’t get involved in EMC compliance testing by themselves and are not familiar with EMC standards.

Traditional EM solvers are not designed specifically for EMC testing and do not generate test results that can be correlated to measurement results for EMC compliance.

An Ideal Simulation tool for EMC testing

An ideal EMC simulation software should be designed to be used as a virtual EMC test lab environment so that the user could go through the same process of getting products tested as in an EMC measurement lab. It should follow the same steps performed in EMC measurements, keeping the complexity of EM solver to run in the background of the simulation.

Figure 1: Measurement lab Vs a Simulation lab

 A well-designed simulation software will enable the hardware engineers to make the best of both worlds. It will not only allow the engineer to understand the product’s EMC behavior by running simulations in a virtual lab. But will also help the engineer validate the product for EMC compliance in a measurement lab.

The simulation analysis and diagnostics help to understand the root cause of the problem to resolve the issues, in the process help in designing EMI resilient products instead of using mitigation methods to resolve EMC problems. Simulations help to understand the physics of the product under test, to characterize the device EMC behavior in running diagnostics to resolve problems. The investigations help to evaluate the coupling paths and analyze the emission sources independently to determine the magnitude and impedance at different points of the coupling path.

Graphical user interface Description automatically generated

Figure 2: Comparing real word EMI to measurement setup and simulation results

Figure 3: Diagnostics and analysis features of Simulation

EMI modeling and simulations have an inherent advantage. During the early stages of design, modeling and simulations can be done even in the absence of any real hardware. Thus, measurements can be carried out even in the absence of a physical product. These benefits make computational modeling a practical choice to determine the EMC behavior of a product when in the development phase.

System-level EMC simulation

In today’s world, using simulation, system-level product design can be done in parallel with the development of the sub-system components of the system. In the same way, system-level EMC simulations can be run in parallel to modeling the EMC behavior of sub-system components, leading to a better understanding on the EMC behavior of the entire system when sub-system components of the system get characterized for their EMC behavior.

Note: The figures and feature examples given above are referenced from Simyog Technology’s simulation software ‘Compliance Scope’. Additional information on the software is available at