Current through a wire is sensed with a shunt resistor and a sense resistor in a current divider circuit. One half of lower plates and one half of upper plates are connected to a first port, and a remaining one half of upper plates and lower plates are connected to a second port, the first and second port having about equal extrinsic capacitance from the lower plates. An inductor a body of ferromagnetic material is securely fixed to the metal body and has a flat surface facing the flat surface of the metal body and an annular recess which defines a central core with a winding arranged therein and a surrounding sleeve. The non-gain sections are arranged on opposite sides of the gain section.