Integrated Circuit EMC Design Questions

3. What can we learn about ICs from near-field scan measurements?

Near magnetic field measurements can provide a great deal of information about where currents are flowing within an IC package without significantly altering those currents. It is possible to create a map of the currents flowing within a package by scanning over the surface with a small magnetic field probe. We can also scan the surface with an electric field probe to get an idea of the voltage distribution within the chip. Near field scans have the advantage that they can be performed without building special circuit boards. Most ICs can be measured in their natural operating environment. A disadvantage of near-field scans is that they require special equipment that is relatively expensive and has limited uses. Also, while near field scans are good for making relative measurements, it is difficult to quantify the currents measured. Converting from a magnetic field measurement to a current requires a fairly detailed knowledge of the geometries involved.

References

[1] X. Dong, S. Deng, D. Beetner, T. Hubing and T. Van Doren, “Determination of high frequency package currents from near-field scan data,” Proc. of the 2005 IEEE International Symposium on Electromagnetic Compatibility, Chicago, IL, USA, Aug. 2005, pp. 679-683.

[2] X. Dong, S. Deng, T. Hubing and D. Beetner, “Analysis of chip-level EMI using near-field magnetic scanning,” Proc. of the 2004 IEEE International Symposium on Electromagnetic Compatibility, Santa Clara, CA, USA, Aug. 2004, pp. 174-177.