In the figure below, the common mode impedances of the line driver and receiver are represented by RCM+ and RC-:
(What I understand by the phrase CM impedance is that it is the resistance or impedance seen by the common mode voltage.)
This CM impedance parameters sometimes are not given in a datasheet directly.
If the CMRR of an amplifier or a transformer ect. is given as 100dB at a particular frequency can we estimate the common mode impedance?
Since -100dB is 10^-5, can we than say the common mode impedance is 100k Ohm?
For instance in this module data-sheet in the second page at specifications, the CMR, the NMR and the input impedance/resistance are explicitly given. Can we also estimate the common mode impedance as well?