Table of contents
foreword
This paper introduces two twisted-pair modeling methods. Through HFSS+Circuit field-circuit co-simulation, the difference in radiated emission between differential lines using twisted-pair and non-twisted-pair architectures is analyzed.
Keywords: twisted pair modeling, field-path coordination, EMC radiated emissions
1. Two modeling methods of twisted pair
Method 1 (Draw Helix): Draw the cable section sheet that needs to be twisted, use the Draw Helix function, set the pitch Pitch and the number of nodes Turn, and perform twisting along the set direction;
Method 2 (Sweep Along Path): Draw the cable cross-section Sheet that needs to be twisted, draw Line along the direction that needs to be twisted, select Sheet and Line, use Sweep Along Path, and set the total degree of twisted wire to 360*N;
Method 2 has a higher degree of freedom in use, and can scan along any line path
2. Field-road collaborative RE simulation
Create a new Circuit project, add the HFSS model to the Circuit, connect the ports of the differential line to the excitation source and the matching resistor, and set Nexxim Transient to solve; after the solution is completed, right-click the
model linked by HFSS, Push Excitations (the simulation in Circuit The results are pushed to HFSS in the form of data import), and the Maximum Frequency can be increased as needed, and the FFT window type is best to choose Hanning;
Observe and compare the 1m method radiation difference of the two structural cables under the same excitation;
Obviously, the radiation level of the differential pair using the twisted pair is lower; (only the field data of three frequency points are saved here, if more frequency points need to be compared, the frequency points of Save Field in the solution settings should be added some )
The reason for the difference in radiation between the two structural cables: the magnetic force lines of the twisted pair always cancel each other out within a unit length;
Pay attention to "Electromagnetic Society" and make electromagnetic simulation no longer complicated!
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