Methods and apparatus for current sensing in mutually coupled inductors

A current sense network for sensing a current in a first inductor mutually coupled to a second inductor, comprising:

• an inductor branch, comprising:
• an inductor exhibiting a series parasitic DC resistance (DCR) and comprising an input node and an output node, wherein:
• the input node is coupled to a branch voltage signal;
• and
• the output node generates an output voltage signal responsive to the branch voltage signal;
• a resistive capacitive (RC) sense circuit comprising a resistor and a capacitor in a series combination, wherein:
• the RC sense circuit is coupled to the input and output nodes of the inductor branch in parallel with the inductor;
• and
• a voltage across the capacitor generates a sense voltage signal corresponding to the sensed current flowing through the inductor branch;
• and
• a coupling circuit coupled to the RC sense circuit and comprising at least one capacitor, wherein a capacitance of the capacitor is selected according to an inductance between the mutually coupled first inductor and second inductor.

A method of generating a signal corresponding to a current in a first inductor mutually coupled to a second inductor, comprising:

• connecting a sense circuit comprising a series combination of a capacitor and a first resistor in parallel with the first inductor;
• connecting a coupling circuit to the series combination, wherein the coupling circuit includes a coupling capacitor;
• and
• selecting a capacitance of the coupling capacitor according to an inductance of the mutual coupling between the first inductor and the second inductor.