In a communications system that conducts differential data via a pair of wires (12), AC common mode noise is undesirably coupled to the wires (12) in a noisy environment. A hybrid common mode choke, HCMC (16), attenuates the AC common mode noise while passing the differential data to a PHY (150). The HCMC (16) includes a CMC (20) (windings with the same polarity) and a differential mode choke (24) (windings with opposite polarities). The CMC (20) attenuates the AC common mode noise, and the DMC (24) passes the attenuated AC common mode noise to termination circuity (26) to eliminate it. Also disclosed is a technique for Kelvin sensing the DC voltage at the pair of wires (12), in a PoDL system, by detecting the voltage on wires (12) that do not carry DC current, so as to provide a more accurate measurement.