Power over data lines system using pair of differential mode chokes for coupling DC voltage and attenuating common mode noise

A Power over Data Lines (PoDL) circuit for connection to a first wire and a second wire of a wire pair, the wire pair for connection to a powered device, the circuit comprising:

• a transceiver having a first terminal and a second terminal, the transceiver for transmitting differential data over the first wire and the second wire and receiving differential data from the first wire and the second wire;
• a first AC-coupling device coupled to the first terminal;
• a second AC-coupling device coupled to the second terminal;
• a first common mode choke (CMC) having a first winding coupled in series between the first AC-coupling capacitor and a third terminal of the PoDL circuit for connection to the first wire, and a second winding coupled in series between the second AC-coupling capacitor and a fourth terminal of the PoDL circuit for connection to the second wire;
• termination circuitry coupled to the third terminal and the fourth terminal, between the wire pair and the first CMC, for terminating the first wire and the second wire to reduce reflections;
• a first differential mode choke (DMC) coupled to nodes between the first CMC and the transceiver;
• a first inductor having one end coupled to a first node between the first CMC and the third terminal, between the wire pair and the first CMC;
• and
• a second inductor having one end coupled to a second node between the first CMC and the fourth terminal, between the wire pair and the first CMC.

A method performed by a Power over Data Lines (PoDL) circuit connected to a first wire and a second wire of a wire pair, the wire pair for connection to a powered device, the method comprising:

• transmitting differential data over the first wire and the second wire and receiving differential data from the first wire and the second wire by a transceiver having a first terminal and a second terminal;
• blocking DC voltages from being applied to the first terminal and the second terminal;
• conducting the differential data through a first common mode choke (CMC) having a first winding coupled in series between the transceiver and the first wire, and a second winding coupled in series between the transceiver and the second wire;
• terminating the first wire and the second wire with termination circuitry to reduce reflections, the termination circuitry being connected between the wire pair and the first CMC;
• and
• supplying DC power to the wire pair by a power supply coupled to a first differential mode choke (DMC) and a second DMC, such that DC power and differential data are transmitted over the first wire and the second wire,
• wherein the first DMC is coupled to nodes between the first CMC and the transceiver,
• wherein the second DMC is coupled to nodes between the first CMC and the wire pair.