Circuits and methods for processing signals generated by a plurality of magnetic field sensing elements

A method of determining a direction of a directional magnetic field, comprising:

• tracking the direction of the directional magnetic field, wherein the directional magnetic field has a first direction subject to a rotation to a second different direction, wherein the tracking comprises:
• receiving the directional magnetic field with a plurality of magnetic field sensing elements for generating a corresponding plurality of magnetic field sensing element signal values;
• selecting a peak magnetic sensing element among the plurality of magnetic field sensing elements that is expected to generate a largest magnetic field sensing element signal value as a peak magnetic field sensing element signal value;
• converting the peak magnetic field sensing element signal value with a first analog-to-digital converter to generate a first converted signal;
• selecting a next peak magnetic sensing element among the plurality of magnetic field sensing elements that is expected to generate a new largest magnetic field sensing element signal value as a next peak magnetic field sensing element signal value when the magnetic field rotates to the second different direction;
• converting the next peak magnetic field sensing element signal value with a second different analog-to-digital converter to generate a second converted signal;
• calculating whether the direction of the magnetic field is closer to the first direction or to the second direction;
• and
• switching back and forth between the converting the peak magnetic field sensing element signal value and the converting the next peak magnetic field sensing element signal value using two different analog-to-digital converters, wherein at least one of the above steps is performed by a processor.

An electronic circuit for determining a largest direction of a directional magnetic field, the electronic circuit comprising:

• an initialization processor coupled to:
• receive a plurality of magnetic field sensing element signals generated by a corresponding plurality of magnetic field sensing elements for generating a plurality of magnetic field sensing element signal values, where in the initialization processor is configured to:
• generate a table of difference values comprising a plurality of difference values, each difference value computed as a respective difference between an identified respective sine value of a sinusoid, the sinusoid having a plurality of sine values, and a ninety-degree sine value of the sinusoid taken ninety degrees apart from the identified respective sine value, wherein one of the identified sine values is at a peak value of the sinusoid and other identified sine values are at selected phase increments of the sinusoid, wherein the plurality of sine values of the sinusoid is irrespective of the plurality of magnetic field sensing element signal values, wherein the electronic circuit further comprises:
• a find peak processor coupled to the initialization processor and configured to:
• select a peak magnetic field sensing element from among the plurality of magnetic field sensing elements that generates a largest one of the plurality of magnetic field sensing element signal values as a peak magnetic field sensing element signal value;
• and
• a track peak processor coupled to receive the table of difference values, coupled to receive the peak magnetic field sensing element signal value, and configured to:
• select a ninety degree magnetic field sensing element from among the plurality of magnetic field sensing elements that has a primary response axis about ninety degrees rotated from a direction of a primary response axis of the peak magnetic field sensing element, the ninety degree magnetic field sensing element generating a ninety degree magnetic field sensing element signal value;
• compute a difference between the peak magnetic field sensing element signal value and the ninety degree magnetic field sensing element signal value, and to
• compare the computed difference with the table of difference values to identify the direction of the magnetic field.

An electronic circuit for determining a direction of a directional magnetic field that has a first direction subject to a rotation to a second different direction, comprising:

• a plurality of magnetic field sensing elements configured to generate a corresponding plurality of magnetic field sensing element signal values, the plurality of magnetic field sensing element signal values responsive to the directional magnetic field;
• a track peak processor configured to:
• select a peak magnetic sensing element among the plurality of magnetic field sensing elements that is expected to generate a largest magnetic field sensing element signal value as a peak magnetic field sensing element signal value;
• a first analog-to digital converter configured to:
• convert the peak magnetic field sensing element signal value to generate a first converted signal;
• the track peak processor further configured to:
• select a second different magnetic sensing element among the plurality of magnetic field sensing elements and proximate to the identified peak magnetic field sensing element as a next peak magnetic field sensing element that is expected to generate a new largest magnetic field sensing element signal value as a next peak magnetic field sensing element signal value when the directional magnetic field rotates to the second different direction;
• a second analog-to-digital configured to:
• convert the next peak magnetic field sensing element signal value to generate a second converted signal,
• Wherein the track peak processor is coupled to receive the first and second converted signals and is further configured to:
• calculate whether the direction of the magnetic field is closer to the first direction or to the second direction, and to
• switch back and forth between the converting the peak magnetic field sensing element signal value and the converting the next peak magnetic field sensing element signal value using two different analog-to-digital converters.

A method of processing signals generated by a plurality of magnetic field sensing elements, comprising:

• exposing the plurality of magnetic field sensing elements to a rotating magnetic field;
• recording maxima and minima signal values for each one of the plurality of magnetic field sensing elements as the rotating magnetic field rotates;
• selecting a first one of the plurality of magnetic field sensing elements as a basis magnetic field sensing element having a basis maximum signal value and a basis minimum signal value;
• computing a plurality of initial offset correction values associated with the plurality of magnetic field sensing elements by computing a difference between the basis maximum signal value and the maximum value for each one of the maximum signal values;
• and
• correcting the signals generated by the plurality of magnetic field sensing elements by using the initial offset correction values, wherein at least one of the above steps is performed by a processor.

An electronic circuit for processing signals generated by a plurality of magnetic field sensing elements, comprising:

• an initialization processor coupled to:
• receive the signals generated by a plurality of magnetic field sensing elements while the plurality of magnetic field sensing elements are exposed to a rotating magnetic field, wherein the initialization processor is configured to:
• select a first one of the plurality of magnetic field sensing elements as a basis magnetic field sensing element having a basis maximum signal value and a basis minimum signal value;
• compute a plurality of initial offset correction values associated with the plurality of magnetic field sensing elements by computing a difference between the basis maximum signal value and the maximum value for each one of the maxima signal values;
• and to
• correct the signals generated by the plurality of magnetic field sensing elements by using the initial offset correction values.