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AN4511

The main parameters

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The main parameters

This section shows how to measure the common mode and the differential mode

impedance, see Figure 7. The equipment can be an impedance meter such as the E4991A

from Agilent technology, working up to 3 GHz.

Figure 7. Differential and common mode impedance measurement

Figure 8 shows the variation of impedance versus frequency. Differential impedance at low

frequency represents the sum of inductance resistances of the filter.

Figure 8. Typical common mode and differential mode impedance vs. frequency

(ECMF04-4HSM10)

However, CMF can be chosen by using insertion losses. Two main parameters are defined:

•

specific frequency range

•

signal without distortion