Current sensor assemblies for low currents

A current sensor assembly, comprising:

• a coil structure having a first coil and a second coil connected in series, the coil structure configured to generate a differential magnetic field responsive to an electrical current passing through the first and second coils;
• a first magnetic field sensing element disposed proximate to the first coil and operable to generate a first signal responsive to the differential magnetic field passing through the first magnetic field sensing element in a first direction;
• a second magnetic field sensing element disposed proximate to the second coil and operable to generate a second signal responsive to the differential magnetic field passing through the second magnetic field sensing element in a second direction;
• and
• a circuit operable to subtract the first and second signals to generate a differential signal proportional to the electrical current;
• wherein the coil structure is formed upon a printed circuit board (PCB) and wherein the first and second magnetic field sensing elements are disposed over the PCB;
• wherein the first coil and the second coil are formed upon a first layer of the PCB and wherein the first coil and the second coil are connected by a conductive path formed upon a second layer of the PCB;
• wherein the coil structure further has a third coil and a fourth coil configured to contribute to the differential magnetic field responsive to the electrical current passing through the third and fourth coils;
• and
• wherein the third and fourth coils are formed upon the second layer of the PCB and connected to the first and second coils, respectively, by vias of the PCB.