I was reading a page on the Recom site (https://recom-power.com/en/rec-n-very-low-noise-filter-for-isolated-dc!sdc-converters-46.html?3) where they devised a filter setup to achieve very low noise on on of their DC-DC converters. The final circuit is as follows:
But I am trying to understand how the common mode chokes L1 and L2 are actually blocking common mode voltages since in either case there is no connection back to the "ground" to which the common mode voltage is referenced to. I thought C3 might be the path but it is before the choke.
Would these still be operating as common mode chokes in this configuration? (ie. L1 blocks common mode voltages on Vin terminal, L2 blocks common mode voltages on Vout terminals)