74
Level 1: 6.6 sec. (Selected area entire scanner, 1,218 probes activated)
Level 2: 1.6 sec. (Selected area 2.25 cm x 2.25 cm, 9 probes activated)
Level 3: 1.6 sec. (Selected area 2.25 cm x 2.25 cm, 9 probes activated)
Level 4: 6.6 sec. (Selected area 2.25 cm x 2.25 cm, 9 probes activated)
Level 5: 23.3 sec. (Selected area 2.25 cm x 2.25 cm, 9 probes activated)
Level 6: 1 min. 30 sec. (Selected area 2.25 cm x 2.25 cm, 9 probes activated)
Level 7: 9 min. 00 sec. (Selected area 2.25 cm x 2.25 cm, 9 probes activated)
13. I am designing multiple layer boards. How can EMxpert help to diagnose EM problems?
Currently, there are no measurement techniques on the market that can exactly see what is going on
inside a multi-layer board. A chamber for example, will only deal with far-field and will not differentiate
between what is coming from the edge, the most external layer, the internal layers, and the interaction
between the layers. It is the most blind of all EMI test solutions to help design a better PCB with EMI
reduction at the source. Automated single probe, handheld probe, and EMxpert can differentiate at
least between the emission from the edge (where emissions from the internal layers will most likely
escape and emit) and from the surface of the external PCB layers.
If one uses a pre-amplifier, the scanner or probe could pick weaker signals from the internal layers
leaking through the external layers. A comparison of the spectral and spatial analysis with or without
amplification could then help point the source (frequency may help specify a component, and the
location will do as well). Using the Gerber of the inner layers as overlay could help confirm the weaker
emissions comes from a known PCB feature. The EMxpert and automated single probe could handle
that; the handheld probe will not work.
Clearly, the EMxpert and the automated single probe are the only adequate tools for multi-layer PCB
EMI measurements. However, the fact that the EMxpert is much faster and can track intermittent
events through peak hold with continuous scanning, makes it the best solution overall.
EMxpert Software
Appendix - FAQ
