Integrated current sensor using Z-axis magnetoresistive gradiometer and lead frame current

Patent metadata

Field	Value
Publication number	US-10564227-B2
Application number	US-201615570104-A
Country	US
Kind code	B2
Filing date	Apr 21, 2016
Priority date	Apr 27, 2015
Publication date	Feb 18, 2020
Grant date	Feb 18, 2020

Abstract

An integrated current sensor comprising a Z axis gradiometer and a lead frame primary coil, wherein the Z-axis gradiometer is a magnetoresistive Z-axis gradient sensor, comprising a substrate, with two elongated soft magnetic flux concentrators placed upon the substrate. The soft ferromagnetic flux concentrators are located above or below but displaced from a long-axis centerline equidistant from the magnetoresistive sensor strings, such that the combined magnetoresistive sensing unit detects the magnetic field perpendicular to the long-axis center line, and it is configured as a gradiometer sensor bridge. The lead frame serves as the primary coil, and the Z-axis gradiometer is placed above or below a cross-section of the current carrying portion of the lead frame, such that the current detection direction is parallel to the long-axis centerline. This sensor can detect currents of up to 5 to 50 A, it has low power consumption, small size, and fully integrated.

First claim

The invention claimed is:

1. An integrated current sensor using a Z-axis magnetoresistive gradiometer and a lead frame current, comprising a Z axis gradiometer and a lead frame primary coil,
wherein the Z axis gradiometer is a magnetoresistive Z-axis gradient sensor comprising:
a substrate,
two elongated soft magnetic flux concentrators Al and B 1 having a separate gradient feature interval Lg and placed upon the substrate, and
magnetoresistive sensor strings located on the upper surface or the lower surface of the soft magnetic flux concentrators and at two side positions equidistant from a long-axis centerline of the soft magnetic flux concentrators, such that the combined magnetoresistive sensing unit detects the magnetic field perpendicular to the long-axis center line of the soft magnetic flux concentrators, and it is configured as a gradiometer sensor bridge; and

wherein the lead frame primary coil comprises an elongated current detection band placed directly above or below the Z axis gradiometer, the two soft magnetic flux concentrators Al and B 1 are symmetrically placed on two sides of a band center line of the elongated current detection band that is parallel to the long-axis center line of the soft magnetic flux concentrators, and the direction of a detection current in the elongated current detection band is parallel to the direction of the long-axis center line of the soft magnetic flux concentrators,
wherein the integrated current sensor further comprises a secondary coil, wherein the secondary coil comprises two subcoils connected in series and having opposite coiling directions, and each of the subcoils comprises two straight wires symmetrically located on two sides of the long-axis center line of the soft magnetic flux concentrators and having opposite feedback current directions.

2. The integrated current sensor using a Z-axis magnetoresistive gradiometer and a lead frame current according to claim 1 , wherein the subcoils are located between the substrate and the Z-axis gradiometer, or located between the magnetoresistive sensing units of the Z-axis gradiometer and the soft magnetic flux concentrators.

3. The integrated current sensor using a Z-axis magnetoresistive gradiometer and a lead frame current according to claim 1 , wherein the magnetoresistive sensing units are GMR, TMR or AMR magnetoresistive sensing units.

4. The integrated current sensor using a Z-axis magnetoresistive gradiometer and a lead frame current according to claim 1 , wherein the gradient sensor bridge is a full-bridge, half-bridge or quasi-bridge structure.

5. The integrated current sensor using a Z-axis magnetoresistive gradiometer and a lead frame current according to claim 1 , wherein the direction of a feedback magnetic field generated at the magnetoresistive sensor strings by the feedback current in the secondary coil is opposite to the direction of a detection magnetic field generated at the magnetoresistive sensor strings by the detection current in the lead frame primary coil.

6. The integrated current sensor using a Z-axis magnetoresistive gradiometer and a lead frame current according to claim 1 , further comprising a signal processing circuit, wherein a signal output end of the Z-axis gradiometer is connected to the signal processing circuit, and the signal processing circuit determines the value of the detection current according to a detection magnetic field gradient measured by the Z-axis gradiometer.

7. The integrated current sensor using a Z-axis magnetoresistive gradiometer and a lead frame current according to claim 1 , further comprising a signal processing circuit, wherein the signal processing circuit is a negative feedback circuit and comprises a signal amplifier, a power controller and a feedback current collector, and a signal output end of the Z-axis gradiometer is connected to the signal amplifier; the detection current is input at the lead frame primary coil, generates a detection magnetic field at the Z-axis gradiometer, and after signal amplification by the signal amplifier, is input, as a feedback signal, to the power controller connected to the secondary coil; the power controller regulates the feedback current in the secondary coil, such that the detection magnetic field and the feedback magnetic field at the magnetoresistive sensing units cancel each other out, and an output signal at the Z-axis gradiometer is 0; the feedback current collector is connected to the power controller, and the value of the detection current is determined according to the value of the feedback current.

8. The integrated current sensor using a Z-axis magnetoresistive gradiometer and a lead frame current according to claim 6 , wherein the signal processing circuit is an ASIC chip.

9. The integrated current sensor using a Z-axis magnetoresistive gradiometer and a lead frame current according to claim 8 , wherein during packaging, the lead frame primary coil and the Z-axis gradiometer are packaged together, or the lead frame primary coil, the Z-axis gradiometer, the secondary coil and the ASIC chip are packaged together.

10. The integrated current sensor using a Z-axis magnetoresistive gradiometer and a lead frame current according to claim 9 , wherein after packaging, the integrated current sensor further comprises a soft magnetic shield that is placed above the Z-axis gradiometer.

11. The integrated current sensor using a Z-axis magnetoresistive gradiometer and a lead frame current according to claim 1 , wherein the amplitude of the detection current ranges from 5 A to 50 A.

12. The integrated current sensor using a Z-axis magnetoresistive gradiometer and a lead frame current according to claim 1 , wherein the soft magnetic flux concentrator is a soft magnetic alloy consisting of one or more elements of Co, Fe, and Ni.

13. The integrated current sensor using a Z-axis magnetoresistive gradiometer and a lead frame current according to claim 1 , wherein the secondary coil is made of Au, Cu, Ag or Al.

Assignees

• Multidimension Technology Co Ltd

Inventors

• Deak James Geza
• Zhou Zhimin

Classifications

• G01R33/0052

  Manufacturing aspects; Manufacturing of single devices, i.e. of semiconductor magnetic sensor chips (devices based on galvano-magnetic effect or the like H10N50/85) · CPC title

• G01R33/075

  Hall devices configured for spinning current measurements · CPC title

• G01R15/12

  Circuits for multi-testers {, i.e. multimeters}, e.g. for measuring voltage, current, or impedance at will · CPC title

• G01R33/09 Primary

  Magnetoresistive devices · CPC title

• H10W90/756

  between a chip and a stacked lead frame, conducting package substrate or heat sink · CPC title