Patent ID: 8472532

Claim:
An apparatus comprising: a common-mode current sensing circuit configured to receive a common-mode current, the common-mode current sensing circuit comprises a center tap potential feed circuit and receives the common-mode current from a transformer having an input side and an output side; a shunt resistor coupled between the common-mode current sensing circuit and a first low supply node; the transformer has a first primary winding and a second primary winding on the input side, and wherein the center tap potential feed circuit is coupled between the first primary winding and the second primary winding; and wherein the center tap potential feed circuit comprises: one or more components providing a first differential impedance matching resistance located between and coupled to the first primary winding and a first node; one or more components providing a second differential matching resistance located between and coupled to the second primary winding and a second node; one or more components providing a DC blocking capacitance between the first node and the second node; a first center tap capacitance coupled to the first node; and a second center tap capacitance coupled to the second node.