Sensor package including a magnetic field sensor and a continuous coil structure for enabling z-axis self-test capability
View Patent ↗A magnetic field sensor includes in-plane sense elements located in a plane of the magnetic field sensor and configured to detect a magnetic field oriented perpendicular to the plane. A current carrying structure is positioned proximate the magnetic field sensor and includes at least one coil surrounding the in-plane sense elements. An electric current is applied to the coil to create a self-test magnetic field to be sensed by the sense elements. The coil may be vertically displaced from the plane in which the sense elements are located and laterally displaced from an area occupied by the sense elements to produce both Z-axis magnetic field components and lateral magnetic field components of the self-test magnetic field. The sense elements are arranged within the coil and interconnected to cancel the lateral magnetic field components, while retaining the Z-axis magnetic field components to be used for self-test of the magnetic field sensor.
1. A sensor package comprising:
a magnetic field sensor, said magnetic field sensor comprising in-plane sense elements located in a plane of said magnetic field sensor and configured to detect a magnetic field oriented perpendicular to said plane, wherein all of said in-plane sense elements are located within an area of said magnetic field sensor;
a continuous coil structure surrounding said area occupied by said in-plane sense elements such that an entirety of said continuous coil structure is laterally displaced outside of said area;
circuitry coupled to said continuous coil structure, said circuitry being configured to provide an electric current to said continuous coil structure to apply a self-test magnetic field to be sensed by said in-plane sense elements, wherein a vector component of said self-test magnetic field is oriented approximately perpendicular to said plane of said magnetic field sensor; and
at least one flux guide configured to direct said vector component of said self-test magnetic field into said plane.
2. The sensor package of claim 1 wherein said continuous coil structure is vertically displaced out of said plane in which said in-plane sense elements are located.
3. The sensor package of claim 1 wherein:
said in-plane sense elements comprise a first magnetoresistive element and a second magnetoresistive element; and
said at least one flux guide comprises:
a first flux guide proximate said first magnetoresistive element and configured to guide said vector component of said self-test magnetic field into said plane in a first direction for detection at said first magnetoresistive element; and
a second flux guide proximate said second magnetoresistive element and configured to guide said vector component of said self-test magnetic field into said plane in a second direction for detection at said second magnetoresistive element, said second direction being oriented opposite to said first direction.
4. The sensor package of claim 3 wherein:
said in-plane sense elements further comprise a third magnetoresistive element and
a fourth magnetoresistive element, wherein said first, second, third, and fourth magnetoresistive elements are electrically connected in a Wheatstone bridge configuration; and
said at least one flux guide further comprises:
a third flux guide proximate said third magnetoresistive element and configured to guide said vector component of said self-test magnetic field into said plane in said first direction for detection at said third magnetoresistive element; and
a fourth flux guide proximate said second magnetoresistive element and configured to guide said vector component of said self-test magnetic field into said plane in said second direction for detection at said fourth magnetoresistive element.
5. The sensor package of claim 1 wherein said continuous coil structure comprises multiple serially connected coils entirely surrounding said area occupied by said in-plane sense elements.
6. A sensor package comprising:
a magnetic field sensor, said magnetic field sensor comprising in-plane sense elements located in a plane of said magnetic field sensor and configured to detect a magnetic field oriented perpendicular to said plane, wherein all of said in-plane sense elements are located within an area of said magnetic field sensor, said in-plane sense elements comprising a first magnetoresistive element, a second magnetoresistive element, a third magnetoresistive element, and a fourth magnetoresistive element, wherein said first, second, third, and fourth magnetoresistive elements are coupled in a Wheatstone bridge configuration, and wherein said first and second magnetoresistive sense elements are connected in parallel, said first and fourth magnetoresistive sense elements are coupled in series, and said second and third magnetoresistive sense elements are coupled in series;
a continuous coil structure surrounding said area occupied by said in-plane sense elements such that an entirety of said continuous coil structure is laterally displaced outside of said area, wherein said continuous coil structure comprises:
a first segment;
a second segment coupled with said first segment;
a third segment coupled with said second segment; and
a fourth segment coupled with said third segment, said first and third segments being located on first opposing edges of said area of said sensor package at which said in-plane sense elements are located, and said second and fourth segments being located on second opposing edges of said area, wherein said first and second magnetoresistive elements are positioned proximate said first segment, and said third and fourth magnetoresistive elements are positioned proximate said third segment; and
circuitry coupled to said continuous coil structure, said circuitry being configured to provide an electric current to said continuous coil structure to apply a self-test magnetic field to be sensed by said in-plane sense elements.
7. The sensor package of claim 6 wherein said current is configured to generate said self-test magnetic field having a lateral vector component in a direction substantially parallel to said plane of said magnetic field sensor wherein the position of said first and second magnetoresistive elements proximate said first segment, and the position of said third and fourth magnetoresistive elements proximate said third segment results in a cancellation of said lateral vector component of said self-test magnetic field.
8. A sensor package comprising:
a magnetic field sensor, said magnetic field sensor comprising in-plane sense elements located in a plane of said magnetic field sensor and configured to detect a magnetic field oriented perpendicular to said plane, wherein all of said in-plane sense elements are located within an area of said magnetic field sensor, and wherein said in-plane sense elements include:
a first magnetoresistive element;
a second magnetoresistive element;
a third magnetoresistive element; and
a fourth magnetoresistive element, wherein said first, second, third, and fourth magnetoresistive elements are coupled in a Wheatstone bridge configuration, and wherein said first and second magnetoresistive sense elements are connected in parallel, said first and fourth magnetoresistive sense elements are coupled in series, and said second and third magnetoresistive sense elements are coupled in series;
a continuous coil structure surrounding said area occupied by said in-plane sense elements such that an entirety of said continuous coil structure is laterally displaced outside of said area and is vertically displaced out of said plane in which said in-plane sense elements are located;
circuitry coupled to said current carrying structure, said circuitry being configured to provide an electric current to said continuous coil structure to apply a self-test magnetic field to be sensed by said in-plane sense elements, wherein a vector component of said self-test magnetic field is oriented approximately perpendicular to said plane of said magnetic field sensor; and
at least one flux guide configured to direct said vector component of said self-test magnetic field into said plane.
9. The sensor package of claim 8 wherein said at least one flux guide comprises:
a first flux guide proximate said first magnetoresistive element and configured to guide said vector component of said self-test magnetic field into said plane in a first direction for detection at said first magnetoresistive element; and
a second flux guide proximate said second magnetoresistive element and configured to guide said vector component of said self-test magnetic field into said plane in a second direction for detection at said second magnetoresistive element, said second direction being oriented opposite to said first direction;
a third flux guide proximate said third magnetoresistive element and configured to guide said vector component of said self-test magnetic field into said plane in said first direction for detection at said third magnetoresistive element; and
a fourth flux guide proximate said second magnetoresistive element and configured to guide said vector component of said self-test magnetic field into said plane in said second direction for detection at said fourth magnetoresistive element.
10. The sensor package of claim 8 wherein said continuous coil structure comprises:
a first segment;
a second segment coupled with said first segment;
a third segment coupled with said second segment; and
a fourth segment coupled with said third segment, said first and third segments being located on first opposing edges of said area of said sensor package at which said in-plane sense elements are located, and said second and fourth segments being located on second opposing edges of said area, wherein said first and second magnetoresistive elements are positioned proximate said first segment, and said third and fourth magnetoresistive elements are positioned proximate said third segment.
11. The sensor package of claim 10 wherein:
said vector component of said self-test magnetic field is a first vector component;
said current is configured to generate said self-test magnetic field having said first vector component oriented substantially perpendicular to said plane of said magnetic field sensor and a second vector component oriented substantially parallel to said plane; and
the position of said first and second magnetoresistive elements proximate said first segment and the position of said third and fourth magnetoresistive elements proximate said third segment results in a cancellation of said second vector component of said self-test magnetic field such that each of said first, second, third, and fourth magnetoresistive sense elements detect said first vector component.