Do you know EMC/EMI simulation during PCB design process?

Do you really know about EMC/EMI simulation in the PCB design process? As the density of electronic devices on the PCB board is getting higher and higher, the traces are getting narrower and the trace density is getting higher and higher, and the frequency of the signals is also increasing. As prices get higher and higher, EMC (Electromagnetic Compatibility) and EMI (Electromagnetic Interference) problems will inevitably be introduced, so the electromagnetic compatibility analysis and application of electronic products is very important. However, the current common situation at home and abroad is that compared with IC design, EMC analysis and simulation in the PCB design process is a weak link. At the same time, EMC simulation analysis is currently playing an increasingly important role in PCB design.

The analysis target signal integrity analysis of EMC/EMI in PCB design includes reflection analysis of the same signal on the same wiring network, impedance matching analysis, signal overshoot analysis, signal timing analysis, etc.; for different signals on adjacent wiring networks crosstalk analysis. The physical topology of the wiring network, the dielectric properties and dielectric constant of the PCB dielectric layer, and the electrical characteristics of each wiring layer must also be considered during signal integrity analysis. There are now international standards for suppressing EMI from electronic equipment and instruments, collectively called electromagnetic compatibility (EMC) standards. They can be used as rules for PCB designers to suppress electromagnetic radiation and interference during wiring and layout. For designers of military electronic products , the standards will be stricter and the requirements will be more demanding. For a system consisting of multiple PCB boards connected through a bus, the electromagnetic compatibility performance between different PCB boards and the EMC/EMI performance of the interface circuits and connectors must also be analyzed.

EMC/EMI simulation requires the use of simulation models. EMC/EMI analysis requires understanding the electrical characteristics of the components used, so that we can better simulate and simulate them specifically. Currently, IBIS and SPICE models are widely used. IBIS (I/O Buffer Interface Specification), or ANSI/EIA-656, is a model that quickly and accurately describes the electrical performance of an I/O buffer based on the V/I curve, obtained through measurement or circuit simulation.

In 1990, INTEL took the lead and collaborated with several well-known semiconductor manufacturers to formulate the industry standard IBIS V1.0. After continuous improvement and development, it was updated to IBIS V3.0 in 1997. Now this standard has been adopted by NS, Motorola, Hundreds of semiconductor manufacturers such as TI, IDT, Xilinx, Siemens, Cypress, and VLSI support it. At the same time, RDA companies such as Cadence, Mentor, Incases, and Zuken-Redac have also added functional modules related to IBIS in their respective software.

An IBIS file is a text file that is a description of "behavioral" information generated in a standard software format to illustrate the analog electrical characteristics of an IC. The SPICE model of IC is a trade secret of each semiconductor manufacturer and is protected by intellectual property rights. The IBIS model is completely open data to users, so designers can easily obtain the IBIS model. Of course, if there is a SPICE model, the IBIS model can be generated from the SPICE model. At present, IBIS models can generally be obtained from device manufacturers.

Apply EMC/EMI simulation to improve the quality of PCB design. After the PCB layout and routing is completed, EMC/EMI analysis and simulation of the circuit design is performed before the GERBER file is made into a circuit board. At the same time, the signal strength, delay and other characteristics are analyzed based on the dynamic operating frequency of the actual circuit. If the designed PCB contains an interface with the outside, a heat sink is added to the IC, or the circuit itself consumes a lot of power, further simulation analysis of electromagnetic radiation must be performed. For high-speed circuits, it is necessary to analyze the transmission line distribution parameters of the wiring network.

EDA development manufacturers are gradually realizing the needs of users in the field of EMC/EMI simulation. The German INCASES company provides designers with the EMC/EMI simulation analysis software package EMC-WORKBENCH, becoming a leader in the industry and hosting many conferences. IEEE Symposium on EMC/EMI. EMC-WORKBENCH can meet the urgent needs of circuit designers in electromagnetic compatibility, improve the PCB design process, and simplify many complicated tasks in later hardware debugging.

At the same time, EMC/EMI issues must also be fully considered within the IC. At present, most chip manufacturers will deal with the EMC/EMI issues inside the IC. However, designers should also pay attention to possible problems in the chip, and at the same time, solve EMC/EMI to the extreme on the board. Electronic engineers can use simulation tools and effectively integrate design experience to better improve product quality and product reliability. The above is the EMC/EMI simulation analysis in the PCB design process. I hope it can help you.