Magnetic field sensor apparatus

• US 7,474,093 B2
• Filed: 09/25/2007
• Issued: 01/06/2009
• Est. Priority Date: 09/25/2006
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Ausserlechner, Udo
• Primary Examiner(s): LEDYNH, BOT L
• Application Number:
  US11/860,959
• Publication Number:
  US 20080074108A1
• Time in Patent Office: 469 Days
• Field of Search: 324/207.14, 324/207.2, 324/207.25, 324/244, 324/251, 324/252, 702/130, 702/138, 702/145, 73766-767, 737/74, 737/77, 737/79
• US Class Current: 324/244
• CPC Class Codes: G01R 33/07 Hall effect devices
• CPC Class Codes: G01R 33/075 Hall devices configured for spinning current measurements
• CPC Class Codes: G01R 33/1207 Testing individual magnetic storage devices, e.g. records carriers or digital storage elements functional testing G06F11/00, G06F11/28

Abstract

A magnetic field sensor apparatus includes a first magnetic field sensor and a second magnetic field sensor, arranged on a substrate in a spaced manner from each other, a first temperature sensor with an output for a first temperature sensor signal, a second temperature sensor with an output for a second temperature sensor signal, a first stress sensor with an output for a first stress sensor signal, and a second stress sensor with an output for a second stress sensor signal, wherein the first temperature sensor and the first stress sensor are arranged more closely to the first magnetic field sensor or at a location identical with the first magnetic field sensor, and the second temperature sensor and the second stress sensor are arranged more closely to the second magnetic field sensor than to the first magnetic field sensor or at a location identical with the second magnetic field sensor.

Claims

1. A magnetic field sensor apparatus, comprising:

a first magnetic field sensor and a second magnetic field sensor, arranged on a substrate in a spaced manner from each other;

a first temperature sensor with an output for a first temperature sensor signal;

a second temperature sensor with an output for a second temperature sensor signal;

a first stress sensor with an output for a first stress sensor signal; and

a second stress sensor with an output for a second stress sensor signal;

wherein the first temperature sensor and the first stress sensor are arranged more closely to the first magnetic field sensor than to the second magnetic field sensor, and the second temperature sensor and the second stress sensor are arranged more closely to the second magnetic field sensor than to the first magnetic field sensor.

2. The magnetic field sensor apparatus according to claim 1, wherein the first temperature sensor is arranged so closely to the first magnetic field sensor, and the second temperature sensor is arranged so closely to the second magnetic field sensor that a temperature difference between a temperature at the first temperature sensor and a temperature at the first magnetic field sensor and a temperature difference between a temperature at the second temperature sensor and a temperature at the second magnetic field sensor each are in a range of less than 0.2 times a temperature difference between the temperature at the first magnetic field sensor and the temperature at the second magnetic field sensor.

3. The magnetic field sensor apparatus according to claim 1, wherein the first stress sensor is arranged so closely to the first magnetic field sensor and the second stress sensor is arranged so closely to the second magnetic field sensor that a stress difference between a stress at the first stress sensor and a stress at the first magnetic field sensor and a stress difference between a stress at the second stress sensor and a stress at the second magnetic field sensor each are in a range of less than 0.2 times a stress difference between the stress at the first magnetic field sensor and the stress at the second magnetic field sensor.

4. The magnetic field sensor apparatus according to claim 1, further comprising:

an evaluator;

wherein the first magnetic field sensor comprises a first output for a first magnetic field sensor signal, and the second magnetic field sensor comprises an output for a second magnetic field sensor signal;

wherein the evaluator comprises an input for the first temperature sensor signal, an input for the second temperature sensor signal, an input for the first stress sensor signal, an input for the second stress sensor signal, and an output for an output signal;

wherein a value of the output signal of the evaluator depends on a ratio of a value of the first magnetic field sensor signal to a value of the second magnetic field sensor signal, the first stress sensor signal, the second stress sensor signal, the first temperature sensor signal and the second temperature sensor signal; and

wherein the output signal provides a determined value of a ratio of a first magnetic field at the first magnetic field sensor to a magnetic field at the second magnetic field sensor, so that an influence of a temperature difference between a temperature at the first magnetic field sensor and a temperature at the second magnetic field sensor and of a stress difference between a stress at the first magnetic field sensor and a stress at the second magnetic field sensor is reduced to the determined value of the ratio.

5. The magnetic field sensor apparatus according to claim 4, wherein the evaluator comprises a temperature difference calculator with an input for the first temperature sensor signal, an input for the second temperature sensor signal and an output for a temperature difference signal dependent on a difference of a value of the first temperature sensor signal and a value of the second temperature sensor signal.

6. The magnetic field sensor apparatus according to claim 5, wherein the evaluator comprises a stress difference calculator with an input for the first stress sensor signal, an input for the second stress sensor signal and an output for a stress difference signal dependent on a difference of a value of the first stress sensor signal and a value of the second stress sensor signal.

7. The magnetic field sensor apparatus according to claim 6, wherein the evaluator comprises a magnetic field ratio determinator with an input for the first magnetic field sensor signal, an input for the second magnetic field sensor signal and an output for a magnetic field ratio signal dependent on a ratio of the value of the first magnetic field sensor signal to the value of the second magnetic field sensor signal.

8. The magnetic field sensor apparatus according to claim 7, wherein the evaluator comprises a calculator with an input for the temperature difference signal, an input for the stress difference signal, an input for the magnetic field ratio signal and an output for a compensation signal;

wherein a value of the compensation signal depends on a value of the temperature difference signal, a value of the stress difference signal and a value of the magnetic field ratio signal, so that the value of the compensation signal corresponds to a value of the magnetic field ratio signal multiplied by a rational function of a numerator and a denominator polynomial with fixed coefficients and powers;

wherein the fixed coefficients and powers comprise coefficients and powers of the temperature difference between the temperature of the first magnetic field sensor and the temperature of the second magnetic field sensor and the stress difference between the stress at the first magnetic field and the stress at the second magnetic field sensor.

9. The magnetic field sensor apparatus according to claim 1, wherein a distance between the first magnetic field sensor and the second magnetic field sensor is in a range above 0.5 times a root of a chip area of a chip on which the first magnetic field sensor and the second magnetic field sensor are arranged.

10. The magnetic field sensor apparatus according to claim 1, wherein the first stress sensor comprises a first elongated doped zone and a second elongated doped zone, in which a doping each is higher than a basic doping of the substrate in which the first stress sensor is implemented, or which comprise a doping type opposite to the basic doping, wherein the first elongated doped zone and the second elongated doped zone are arranged at an angle ranging from 80°

to 100°

with respect to each other.

11. The magnetic field sensor apparatus according to claim 1, wherein the first stress sensor and the first magnetic field sensor are implemented in a single device, wherein the magnetic field sensor apparatus comprises an input for an impressed current and a tap for a potential, the value of which depends on the impressed current and a mechanical stress at the first magnetic field sensor.

12. The magnetic field sensor apparatus according to claim 11, wherein the second stress sensor comprises a first elongated doped zone and a second elongated doped zone, in which a doping each is higher than a basic doping of the substrate in which the second stress sensor is implemented, or which comprise a doping type opposite to the basic doping, wherein the elongated doped zones are arranged at an angle ranging from 80°

to 100°

with respect to each other.

13. The magnetic field sensor apparatus according to claim 10, wherein the second stress sensor and the second magnetic field sensor are implemented in one device, and the second magnetic field sensor comprises an input for a further impressed current and a tap for a further potential, the value of which depends on the further impressed current and the mechanical stress at a second Hall sensor.

14. The magnetic field sensor apparatus according to claim 1, further comprising a third stress sensor arranged on the substrate more closely to the first magnetic field sensor than to the second magnetic field sensor, so that the first magnetic field sensor is arranged between the first stress sensor and the third stress sensor.

15. The magnetic field sensor apparatus according to claim 14, wherein the third stress sensor comprises two elongated doped zones, the doping of which each is higher than a basic doping of the substrate in which the third stress sensor is implemented, or which comprise a doping type different from the basic doping, wherein the two elongated doped zones are arranged at an angle ranging from 80°

to 100°

.

16. The magnetic field sensor apparatus according to claim 14, further comprising a fourth stress sensor, which is arranged on the substrate more closely to the second magnetic field sensor than to the first magnetic field sensor, so that the second magnetic field sensor is arranged between the second stress sensor and the fourth stress sensor.

17. The magnetic field sensor apparatus according to claim 16, wherein the fourth stress sensor comprises two elongated doped zones, the doping of which each is higher than a basic doping of the substrate in which the fourth stress sensor is implemented, or which comprise a doping type different from the basic doping, wherein the two elongated doped zones are arranged at an angle ranging from 80°

to 100°

.

18. The magnetic field sensor apparatus according to claim 17, wherein the first, the second, the third and the fourth stress sensor each comprise a first and a second terminal;

wherein the first, the second, the third and the fourth stress sensor are coupled together in a bridge circuit;

wherein a first terminal of the first stress sensor is electrically connected to a first terminal of the second stress sensor in effective manner, and a second terminal of the first stress sensor is electrically connected to a first terminal of the fourth stress sensor in effective manner;

wherein a second terminal of the second stress sensor is electrically connected to a first terminal of the third stress sensor in effective manner, and a second terminal of the third stress sensor is electrically connected to a second terminal of the fourth stress sensor in effective manner; and

wherein the second terminal of the third stress sensor and the first terminal of the second stress sensor form an input for an input signal of the bridge circuit, and the second terminal of the first stress sensor and the second terminal of the second stress sensor form an output for an output signal of the bridge circuit, the value of which is dependent on a difference of a stress at the first magnetic field sensor and a stress at the second magnetic field sensor.

19. The magnetic field sensor apparatus according to claim 1, wherein the first magnetic field sensor and the second magnetic field sensor are arranged on the substrate so that, when applying a first input voltage to the first magnetic field sensor, a first impressed current flows and, when applying a second input voltage to the second magnetic field sensor, a second impressed current flows, wherein the first impressed current and the second impressed current form an angle ranging from 170°

to 190°

or ranging from 350°

to 10°

.

20. The magnetic field sensor apparatus according to claim 1, wherein the first temperature sensor comprises a first band-gap circuit with an output for the first temperature sensor signal, the value of which is proportional to an absolute temperature at the first magnetic field sensor.

21. The magnetic field sensor apparatus according to claim 1, wherein the second temperature sensor comprises a second band-gap circuit with an output for the second temperature sensor signal, the value of which is proportional to an absolute temperature at the second magnetic field sensor.

22. The magnetic field sensor apparatus according to claim 8, wherein the calculator comprises the output for the compensation signal, the value of which depends on the following formula:

$V_3=\frac{S_{h,2}<br><br>\left(T_2\right)}{S_{h,1}<br><br>\left(T_1\right)}<br><br>\frac{1}{\begin{array}{c}1+\mathrm{\kappa <br><br>}<br><br>\left(T\right)<br><br>\frac{\left(S_{\mathrm{\sigma <br><br>}}-{\mathrm{\mu <br><br>}}_{\mathrm{\sigma <br><br>}}\right)<br><br>\mathrm{\zeta <br><br>}<br><br>\left(T\right)-\left(S_T-{\mathrm{\mu <br><br>}}_T\right)<br><br>{\mathrm{\pi <br><br>}}_n<br><br>\left(T\right)}{{\mathrm{\varepsilon <br><br>}}^{\mathrm{\prime <br><br>}}<br><br>\mathrm{\zeta <br><br>}<br><br>\left(T\right)-{\mathrm{\delta <br><br>}}^{\mathrm{\prime <br><br>}}<br><br>{\mathrm{\pi <br><br>}}_n<br><br>\left(T\right)}+\\ P<br><br>\left(T\right)<br><br>\frac{\left(S_T-{\mathrm{\mu <br><br>}}_T\right)<br><br>{\mathrm{\varepsilon <br><br>}}^{\mathrm{\prime <br><br>}}-\left(S_{\mathrm{\sigma <br><br>}}-{\mathrm{\mu <br><br>}}_{\mathrm{\sigma <br><br>}}\right)<br><br>{\mathrm{\delta <br><br>}}^{\mathrm{\prime <br><br>}}}{{\mathrm{\varepsilon <br><br>}}^{\mathrm{\prime <br><br>}}<br><br>\mathrm{\zeta <br><br>}<br><br>\left(T\right)-{\mathrm{\delta <br><br>}}^{\mathrm{\prime <br><br>}}<br><br>{\mathrm{\pi <br><br>}}_n<br><br>\left(T\right)}\end{array}}=\frac{B_2}{B_1}$

wherein V₃ represents a value of the ratio, T₁ represents a value of the temperature at the first magnetic field sensor, T₂ represents a value of the temperature at the second magnetic field sensor, B₁ defines a value of the magnetic field at the first magnetic field sensor, B₂ defines a value of the magnetic field at the second magnetic field sensor, S_h,1 represents a value of the first magnetic field sensor output signal, S_h,2 represents a value of the second magnetic field sensor output signal, κ

(T) represents a value of a normalized differential current-related magnetic sensitivity of the magnetic field sensor apparatus, S_T represents a value of the temperature difference signal, for which the following applies;

S_T=S_T2−

S_T1

wherein S_T2 represents a value of the second temperature sensor signal, S_T1 represents a value of the first temperature sensor signal, and S_σ

represents a value of the stress difference signal, wherein

S_σ

=S<sub>σ

2</sub>−

S<sub>σ

1</sub>

wherein S<sub>σ

1</sub> indicates a value of the first stress sensor signal, S<sub>σ

2</sub> indicates a value of the second stress sensor signal;

wherein a variable P(T) indicates a value of a temperature-dependent piezo Hall coefficient of the magnetic field sensor apparatus, μ

_t represents a value of the temperature difference signal S_T if the temperature T₁ at the first magnetic field sensor and the temperature T₂ at the second magnetic field sensor are equal to within a tolerance of 2%, the variable μ

_σ

represents a value of the difference signal S_σ

if the mechanical stress at the first magnetic field sensor is equal to the mechanical stress at the second magnetic field sensor to within a tolerance of 2%; and

wherein the variable ζ

(T) represents a temperature-dependent value of a stress dependence of the value S_T of the temperature difference signal, ε

′

indicates a temperature dependence of the value S_σ

of the stress difference signal, δ

′

indicates a temperature sensor sensitivity of the magnetic field sensor apparatus, π

_n indicates a value of the piezoresistive coefficient of the magnetic field sensor apparatus, and the variable T represents a mean temperature of the substrate.

23. The magnetic field sensor apparatus according to claim 1, wherein the first temperature sensor and the first stress sensor are arranged at a location identical with the first magnetic field sensor.

24. The magnetic field sensor apparatus according to claim 1, wherein the second temperature sensor and the second stress sensor are arranged at a location identical with the second magnetic field sensor.