How are the various insertion loss limits measured?
Common mode or asymmetrical insertion loss is measured with all filtered circuits connected in parallel in a 50 Ohm system. The common mode insertion loss of a filter depends upon the combination of the common mode coils, multi-filar wound, as well as the line-to-ground capacitors. Differential mode or symmetrical insertion loss is measured in a 50 Ohm system using 180 transformers which split the signal between the line and neutral conductors with a 180 phase shift as the signal would appear in the real world. The differential mode insertion loss of a filter depends upon the line-to-line capacitors, discrete inductors, as well as the leakage inductance of the common mode coils.
