Inductive proximity sensor

An inductive proximity sensor comprising:

• a multi-receiver coil assembly comprising:
• a first receiver;
• a second receiver arranged in a differential coil arrangement with the first receiver;
• and
• a transmitter configured to:
• emit an electromagnetic field;
• inductively couple with the first receiver to induce a first voltage on the first receiver;
• and
• inductively couple with the second receiver to induce a second voltage on the second receiver;
• and
• an evaluator circuit configured to receive a differential signal from the multi-receiver coil assembly, wherein the evaluator circuit comprises:
• a first resistor configured to receive the first voltage, wherein a first resistance value of the first resistor is determined based on a first tolerance of the first receiver;
• a second resistor configured to receive the second voltage, wherein a second resistance value of the second resistor is determined based on a second tolerance of the second receiver;
• a node configured to electrically couple to the first resistor and the second resistor;
• a filter configured to generate a filtered differential signal by filtering noise from a differential signal generated based on a voltage difference between the first voltage and the second voltage, wherein the filter receives the differential voltage signal via the node;
• an amplifier configured to generate an amplified differential signal by amplifying the differential signal;
• and
• an output circuit configured to determine a change in the amplified differential signal and indicate a detected target based on a comparison of the change with a threshold.

A method of detecting a target with an inductive proximity sensor, the method comprising:

• generating an electromagnetic field at a transmitter to induce a voltage on at least two receivers arranged in a differential coil arrangement;
• generating a differential signal from the at least two receivers based on the voltage and at least two resistors having at least two resistance values, wherein the at least two resistors are coupled with the differential coil arrangement, and wherein the at least two resistance values are determined based on tolerances associated with the at least two receivers;
• filtering the differential signal to generate a filtered differential signal;
• amplifying the filtered differential signal to generate an amplified differential signal;
• sampling the amplified differential signal to generate a sampled differential signal;
• determining a change in the sampled differential signal;
• and
• determining whether a target is detected based only on a comparison between the change and a threshold.