Xmr sensor with continuous-time coil compensation loop
AssigneeAllegro MicroSystems, LLC
InventorTyler Daigle
Life of this patent
Estimating the term…
Abstract
A magnetoresistance sensing device includes an on-chip coil capable of generating a magnetic field measured by a wheat stone bridge. The on-chip coil is used in a compensation loop and constructed in parallel with a main signal path using a separate, matched xMR compensation bridge. The separate xMR bridge allows generating and measuring a compensation signal continuously and differentially, which improves signal fidelity without introducing noise into the primary signal path. One or more chopper switches are provided to eliminate offset and flicker noise.
Claims20
A magnetic field sensor IC package device, comprising:
- a first bridge including a first group of arrays and a second bridge including a second group of arrays, each of the first group of arrays and the second group of arrays having xMR elements, wherein each of the xMR elements has a pinning direction;
- and
- an on-chip coil routed under the xMR elements configured to conduct current for generating a first magnetic field on the xMR elements of the first group of arrays and the second group of arrays, wherein the first group of arrays is configured to sense changes in an applied magnetic field and the second group of arrays is configured to sense a coil-generated magnetic field.
A method comprising:
- arranging a first bridge including a first group of arrays and a second bridge including a second group of arrays, each of the first group of arrays and the second group of arrays having xMR elements, wherein each of the xMR elements has a pinning direction;
- and
- providing an on-chip coil routed under the xMR elements configured to conduct current for generating a first magnetic field on the xMR elements of the first group of arrays and the second group of arrays, wherein the first group of arrays is configured to sense changes in an applied magnetic field and the second group of arrays is configured to sense a coil-generated magnetic field.
A sensing bridge, comprising:
- a first bridge including a first group of arrays and a second bridge including a second group of arrays, each of the first group of arrays and the second group of arrays having xMR elements, wherein each of the xMR elements has a pinning direction;
- an on-chip coil routed under the xMR elements in a serpentine pattern with odd-numbered U-turns skipping adjacent columns of the xMR elements, the on-chip coil configured to conduct current for generating a first magnetic field on the xMR elements of the first group of arrays and the second group of arrays;
- a first frontend gain stage connected to the first group of arrays;
- and
- a second frontend gain stage connected to the second group of arrays and summed with a reference voltage to generate a compensation signal to control an input bias;
- wherein the first group of arrays is configured to sense changes in an applied magnetic field, the second group of arrays is configured to sense a fixed coil-generated magnetic field and is immune to the applied magnetic field.
Dependencies are inferred from the claim text.