Magnetic field sensor with error calculation

A system comprising:

• at least one coil configured to:
• generate a first magnetic field having a first non-zero frequency;
• and
• generate a second magnetic field having a second frequency;
• a conductive target positioned to generate a reflected magnetic field in response to the first magnetic field;
• one or more magnetic field sensing elements configured to:
• produce a first signal representing detection of the first magnetic field and the reflected magnetic field;
• and
• produce a second signal representing detection of the second magnetic field;
• and
• a processing circuit configured to:
• receive the first and second signals;
• and
• calculate an error value of the system as a function of the first and second signals,
• sum the first signal and the second signal to form a summation signal;
• and
• subtract the first signal from the second signal to form a subtraction signal.

A method comprising:

• generating a first magnetic field having a first, non-zero frequency;
• generating a second magnetic field having a second frequency;
• inducing, by the first magnetic field, a reflected magnetic field from a conductive target;
• producing a first signal, by one or more magnetic field sensing elements, representing the first magnetic field and the reflected magnetic field;
• producing a second signal, by the one or more magnetic field sensing elements, representing the second magnetic field;
• and
• calculating an error value as a function of the first and second signals,
• summing the first signal and the second signal to form a summation signal;
• and
• subtracting the first signal from the second signal to form a subtraction signal.

A system comprising:

• a first magnetic field sensing element;
• a second magnetic field sensing element;
• means for generating a first magnetic field having a first non-zero frequency;
• means for generating a second magnetic field having a second frequency;
• a conductive target positioned to generate a reflected magnetic field in response to the first magnetic field;
• means for producing a first signal representing the first magnetic field and the reflected magnetic field during a first alternating time period;
• means for producing a second signal representing the second magnetic field during a second alternating time period;
• means for calculating an error value as a function of the first and second signals, wherein the error value is based, at least in part, on the second signal during the first time period;
• and
• means for applying the error value to the first signal during the first alternating time period.