CPC G01V 3/104 (2013.01) [H02J 50/12 (2016.02); H02J 50/60 (2016.02)] | 18 Claims |
1. An apparatus for detecting an object, the apparatus comprising:
a plurality of sense circuits, each of the plurality of sense circuits comprising:
a primary sense coil and a secondary sense coil configured to inductively sense the object and to have a mutual reactance at an operating frequency; and
a capacitor having a reactance at the operating frequency;
a driver circuit configured to selectively drive a current at the operating frequency in the primary sense coil and the capacitor of each of the plurality of sense circuits; and
a measurement circuit configured to selectively measure a voltage across the secondary sense coil and the capacitor of each of the plurality of sense circuits in response to the current in the primary sense coil and the capacitor;
wherein each of the plurality of sense circuits is configured to:
cause the reactance of the capacitor to substantially compensate for the mutual reactance of the primary and secondary sense coils at the operating frequency; and
cause a transimpedance, defined by the ratio of the voltage and the current, to be substantially resistive at the operating frequency.
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