SENSOR SELF-DIAGNOSTICS USING MULTIPLE SIGNAL PATHS

• US 20120074972A1
• Filed: 09/24/2010
• Published: 03/29/2012
• Est. Priority Date: 09/24/2010
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Motz, Mario, Hammerschmidt, Dirk, Schaffer, Bernhard, Granig, Wolfgang, Rasbornig, Friedrich, Gastinger, Ferdinand
• Granted Patent: US 9,346,441 B2
• Time in Patent Office: Days
• US Class Current: 324/750.3
• CPC Class Codes: B60T 2250/06 Sensor zero-point adjustment; Offset compensation
• CPC Class Codes: B60T 2270/406 Test-mode; Self-diagnosis
• CPC Class Codes: B60T 2270/411 Offset failure
• CPC Class Codes: B60T 2270/413 Plausibility monitoring, cross check, redundancy
• CPC Class Codes: B60T 8/885 using electrical circuitry
• CPC Class Codes: G01D 3/08 with provision for safeguarding the apparatus, e.g. against abnormal operation, against breakdown
• CPC Class Codes: G01R 31/007 using microprocessors or computers
• CPC Class Codes: G01R 31/2644 Adaptations of individual semiconductor devices to facilitate the testing thereof
• CPC Class Codes: G01R 31/2829 Testing of circuits in sensor or actuator systems testing of apparatus for measuring electric or magnetic variables G01R35/00; testing of indicating or recording apparatus G01D; in airbag systems B60R21/0173; checking gas analysers G01N33/007; monitoring or fail-safe circuits for electromagnets H01F7/1844
• CPC Class Codes: G01R 31/2856 Internal circuit aspects, e.g. built-in test features; Test chips; Measuring material aspects, e.g. electro migration [EM]
• CPC Class Codes: G01R 31/2884 using dedicated test connectors, test elements or test circuits on the IC under test G01R31/2855 takes precedence
• CPC Class Codes: G01R 31/3187 Built-in tests
• CPC Class Codes: H01L 2224/13144 Gold [Au] as principal constituent

Abstract

Embodiments relate to systems and methods for sensor self-diagnostics using multiple signal paths. In an embodiment, the sensors are magnetic field sensors, and the systems and/or methods are configured to meet or exceed relevant safety or other industry standards, such as SIL standards. For example, a monolithic integrated circuit sensor system implemented on a single semiconductor ship can include a first sensor device having a first signal path for a first sensor signal on a semiconductor chip; and a second sensor device having a second signal path for a second sensor signal on the semiconductor chip, the second signal path distinct from the first signal path, wherein a comparison of the first signal path signal and the second signal path signal provides a sensor system self-test.

Claims

1. A monolithic integrated circuit sensor system comprising:

a first sensor device having a first signal path for a first sensor signal on a semiconductor chip; and

a second sensor device having a second signal path for a second sensor signal on the semiconductor chip, the second signal path distinct from the first signal path,

wherein a comparison of the first signal path signal and the second signal path signal provides a sensor system self-test.

2. The sensor system of claim 1, further comprising a digital signal processor (DSP) on the semiconductor chip and coupled to the first and second signal paths to receive the first and second signal path signals, wherein the comparison is implemented by the DSP.

3. The sensor system of claim 2, wherein the DSP comprises at least one of a first software block associated with the first signal path and a second software block associated with the second signal path, or a first digital signal processing portion associated with the first signal path and a second digital signal processing portion associated with the second signal path.

4. The sensor system of claim 2, wherein the DSP is coupled to the first and second signal paths by an analog-to-digital (A/D) conversion channel cross-switching device.

5. The sensor system of claim 1, further comprising at least one additional sensor device coupled to the second signal path to provide a comparison signal.

6. The sensor system of claim 5, wherein the at least one additional sensor device is selected from the group consisting of a temperature sensor, a stress sensor, a current sensor, a voltage sensor and a magnetic field sensor.

7. The sensor system of claim 5, further comprising a multiplexer on the semiconductor chip and coupling the second sensor device and the at least one additional sensor device to the second signal path.

8. The sensor system of claim 1, wherein the first and second sensor devices comprise magnetic field sensors.

9. The sensor system of claim 1, wherein the first signal path comprises a first analog-to-digital (A/D) converter and the second signal path comprises a second A/D converter different from the first A/D converter.

10. The sensor system of claim 9, wherein the first A/D converter operates with at least one working principle distinct from a working principle of the second A/D converter.

11. The sensor system of claim 1, further comprising a first biasing circuit coupled to the first sensor device and the first signal path, and a second biasing circuit coupled to the second sensor device and the second signal path.

12. The sensor system of claim 11, further comprising a biasing comparator configured to receive a signal from the first biasing circuit and a signal from the second biasing circuit and to compare the signals.

13. The sensor system of claim 1, wherein the first signal path, when compared with the second signal path, has at least one characteristic selected from the group consisting of being faster, being more precise, having less noise and having a different working principle.

14. The sensor system of claim 1, wherein the sensor system meets a Safety Integrity Level (SIL) standard.

15. A method of providing a self-test in a monolithic integrated circuit sensor system comprising:

implementing, on a single semiconductor chip, a main signal path comprising a main sensor;

implementing, on the single semiconductor chip, a secondary sensor and a secondary signal path, the secondary signal path distinct from the main signal path and, when compared with the main signal path, having at least one characteristic selected from the group consisting of being slower, being less precise, having more noise and having a different working principle; and

conducting a self-test of the sensor system by comparing a signal of the main signal path with a signal of the secondary signal path.

16. The method of claim 15, further comprising multiplexing at least one additional sensor to the secondary signal path.

17. The method of claim 16, further comprising receiving at least one compensation signal from the at least one additional sensor.

18. The method of claim 15, further comprising:

implementing a first analog-to-digital (A/D) conversion technique on the main signal path; and

implementing a second A/D conversion technique on the secondary signal path, the second A/D conversion technique different from the main A/D conversion technique.

19. The method of claim 15, further comprising:

biasing the main sensor by a first biasing portion;

biasing the secondary sensor by a second biasing portion different from the first biasing portion; and

measuring a biasing current of the main sensor and a biasing current of the secondary sensor.

20. The method of claim 15, further comprising:

coupling the main and secondary signal paths to a digital signal processor (DSP);

processing the signal of the main signal path using a first software portion of the DSP; and

processing the signal of the secondary signal path using a second software portion of the DSP, the second software portion different from the first software portion.

21. The method of claim 20, further comprising providing parallel outputs of the DSP comprising a main signal path portion and a secondary signal path portion.

22. The method of claim 15, wherein comparing comprises forming at least one of a quotient or a linear transformation of the signal of the main signal path and the signal of the secondary signal path.

23. The method of claim 22, further comprising evaluating the at least one quotient or linear transformation to detect a system failure.

24. The method of claim 15, further comprising adjusting a measurement range of at least one of the main sensor or the secondary sensor.

25. The method of claim 15, further comprising exchanging the main sensor and the secondary sensor such that the main sensor is coupled to the secondary signal path and the secondary sensor is coupled to the main signal path.