Reducing voltage non-linearity in a bridge having tunneling magnetoresistance (TMR) elements
In one aspect, a magnetic field sensor includes a plurality of tunneling magnetoresistance (TMR) elements that includes a first TMR element, a second TMR element, a third TMR element and a fourth TMR element. The first and second TMR elements are connected to a voltage source and the third and fourth TMR elements are connected to ground. Each TMR element has a pillar count of more than one pillar and the pillar count is selected to reduce the angle error below 1.0°.
1. A magnetic field sensor, comprising:
a plurality of tunneling magnetoresistance (TMR) elements comprising a first TMR element, a second TMR element, a third TMR element and a fourth TMR element,
wherein the first and second TMR elements are connected to a voltage source, wherein the third and fourth TMR elements are connected to ground,
wherein each TMR element has a pillar count of more than one pillar,
wherein the pillar count is selected to reduce the angle error below 1.0°.
2. The magnetic field sensor of claim 1 , wherein the pillar count is selected to reduce the angle error below 0.1°, wherein the angle error is caused by voltage nonlinearity.
3. The magnetic field sensor of claim 1 , wherein the pillar count is selected to reduce the angle error below 0.01°, wherein the angle error is caused by voltage nonlinearity.
4. The magnetic field sensor of claim 1 , wherein the pillar count is selected to reduce the angle error below 0.001°, wherein the angle error is caused by voltage nonlinearity.
5. The magnetic field sensor of claim 1 , wherein each TMR element has a voltage drop between 0V and 1.5V.
6. The magnetic field sensor of claim 1 , wherein each TMR element has a voltage drop of 0.5V.
7. The magnetic field sensor of claim 1 , wherein the magnetic field sensor is an angle sensor.
8. The magnetic field sensor of claim 1 , wherein the magnetic field sensor is a linear sensor.
9. The magnetic field sensor of claim 1 , wherein the magnetic field sensor is a rotary sensor.
10. The magnetic field sensor of claim 1 , wherein the voltage source provides a voltage between 0V and 1.5V.
11. The magnetic field sensor of claim 1 , wherein the voltage source provides a voltage between 1.0V.
12. The magnetic field sensor of claim 1 , wherein a reference direction of the first TMR element is opposite a reference direction of the second TMR element.
13. The magnetic field sensor of claim 12 , wherein the reference direction of the first TMR element is opposite a reference direction of the third TMR element.
14. The magnetic field sensor of claim 13 , wherein the reference direction of the first TMR element is equal to a reference direction of the fourth TMR element.
15. The magnetic field sensor of claim 1 , wherein a reference direction of the first, second, third and fourth TMR elements are in the same direction.
16. The magnetic field sensor of claim 1 , wherein each TMR element comprises a free layer that changes with an applied field and a reference layer that is fixed.