MAGNETIC SENSOR READING DEVICE, SYSTEM AND METHOD

• US 20120158324A1
• Filed: 11/22/2011
• Published: 06/21/2012
• Est. Priority Date: 11/26/2010
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Romani, Carlo Alberto, Pozzati, Enrico, Bottinelli, Fabio
• Granted Patent: US 10,473,731 B2
• Time in Patent Office: Days
• US Class Current: 702/57
• CPC Class Codes: G01R 33/0017 Means for compensating offset magnetic fields or the magnetic flux to be measured; Means for generating calibration magnetic fields
• CPC Class Codes: G01R 33/0023 Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration G01R33/0017 takes precedence
• CPC Class Codes: G01R 33/0035 Calibration of single magnetic sensors, e.g. integrated calibration
• CPC Class Codes: G01R 33/06 using galvano-magnetic devices
• CPC Class Codes: G01R 33/09 Magnetoresistive devices
• CPC Class Codes: G01R 33/096 anisotropic magnetoresistance sensors
• CPC Class Codes: G01R 35/00 Testing or calibrating of apparatus covered by the other groups of this subclass

Abstract

A reading circuit for a magnetic-field sensor, provided with a detection structure generating an electrical detection signal as a function of an external magnetic field, has a signal-conditioning stage, which is electrically coupled to the detection structure and generates an output signal as a function of the electrical detection signal; the reading circuit is provided with a full-scale-control stage that is able to select automatically a full-scale value for the signal-conditioning stage, as a function of the value of the external magnetic field, such as to prevent saturation of the same conditioning stage.

Claims

1. A reading circuit, comprising:

a signal processing stage configured to receive a detection signal indicative of one or more characteristics of a magnetic field and to generate an output signal as a function of said detection signal; and

a full-scale control stage communicatively coupled to said signal processing stage and configured to automatically select a full-scale value of said signal processing stage based on the output signal.

2. The circuit according to claim 1 wherein said full-scale control stage is integrated with said signal processing stage in a first die of semiconductor material, and is configured to generate and to send to said signal processing stage a command signal based on the selected full-scale value of said signal processing stage.

3. The circuit according to claim 2 wherein said signal processing stage comprises an amplification unit having an electronically variable and selectable amplification gain, and said amplification stage is configured to vary a value of said amplification gain based on the command signal, the selected full-scale value being a minimum value selected from a set of values which prevents saturation of said signal processing stage.

4. The circuit according to claim 1 wherein said full-scale control stage is configured to iteratively modify the selected full-scale value of said signal processing stage, until an absence of saturation of said output signal is detected.

5. The circuit according to claim 4 wherein said iteratively modifying comprises:

selecting a first full-scale value;

determining whether saturation of the signal processing stage is present at the first full-scale value based on the output of the signal processing stage; and

when it is determined that saturation of the signal processing stage is present, incrementing the first full-scale value.

6. The circuit according to claim 5 wherein said first full-scale value is one of:

a minimum selectable value and a default value.

7. The circuit according to claim 1 wherein said full-scale control stage is configured to:

monitor the output signal to determine whether saturation of the signal processing stage is present at the selected full-scale value; and

when it is determined that saturation of the signal processing stage is present at the selected full-scale value, determine whether saturation is present at a largest available full-scale value.

8. The circuit according to claim 7 wherein the full-scale control stage is configured to, when it determined that saturation is not present at the largest selectable full-scale value, increment the selected full-scale value.

9. The circuit according to claim 1 wherein said full-scale control stage is configured to:

periodically monitor the output signal to determine whether saturation of the signal processing stage is present at the selected full-scale value; and

when saturation is not detected,

determine whether the selected full-scale is lower than a default value; and

if the selected full-scale value is lower than the default value, reset the selected full-scale value to the default value.

10. The circuit according to claim 1 wherein said full-scale control stage has an enabling input and is configured to carry out the automatic selection of said full-scale value in response to reception of an enable signal.

11. The circuit according to claim 1 wherein said magnetic field comprises a useful component and a component of disturbance.

12. A system, comprising:

a detection structure configured to generate an electrical detection signal as a function of a magnetic field; and

a reading circuit, including;

a signal processing stage configured to generate an output signal based on the electrical detection signal generated by the detection structure; and

a full-scale control stage communicatively coupled to said signal processing stage and configured to automatically select a full-scale value of said signal processing stage based on the output signal.

13. The system according to claim 12 wherein said full-scale control stage is integrated with said signal processing stage in a first die of semiconductor material, and is configured to generate and to send to said signal processing stage a command signal based on the selected full-scale value of said signal processing stage.

14. The system according to claim 13 wherein said signal processing stage comprises an amplification unit having an electronically variable and selectable amplification gain, and said amplification stage is configured to vary a value of said amplification gain based on the command signal, the selected full-scale value being a minimum value selected from a set of values which prevents saturation of said signal processing stage.

15. The system according to claim 12 wherein said full-scale control stage is configured to iteratively modify the selected full-scale value of said signal processing stage, until an absence of saturation of said output signal is detected.

16. The system according to claim 15 wherein said iteratively modifying comprises:

selecting a first full-scale value;

determining whether saturation of the signal processing stage is present at the first full-scale value based on the output of the signal processing stage; and

when it is determined that saturation of the signal processing stage is present, incrementing the first full-scale value.

17. The system according to claim 16 wherein said first full-scale value is one of:

a minimum selectable value and a default value.

18. The system according to claim 12 wherein said full-scale control stage is configured to:

monitor the output signal to determine whether saturation of the signal processing stage is present at the selected full-scale value; and

when it is determined that saturation of the signal processing stage is present at the selected full-scale value,

determine whether saturation is present at a largest selectable full-scale value; and

when it determined that saturation is not present at the largest selectable full-scale value, increment the selected full-scale value.

19. The system according to claim 12 wherein said detection structure comprises magnetoresistive elements configured to form a bridge detection structure and said electrical detection is a signal indicative of an unbalancing of said bridge detection structure.

20. The system according to claim 13 wherein said detection structure is made in at least one second die made of semiconductor material, arranged with said first die inside a single package, to form a magnetic-field sensor chip.

21. The system of claim 12, further comprising a management unit, coupled to said reading circuit and configured to receive said output signal.

22. The system according to claim 21 wherein said full-scale control stage has an enabling input and said management unit is configured to send an enabling signal to said full-scale control stage of said reading circuit.

23. A method, comprising:

receiving an electrical detection signal indicative of at least one characteristic of a magnetic field;

generating, using a reading circuit, an output signal based on the electrical detection signal; and

selecting a full-scale value of said reading circuit based on the output signal.

24. The method of claim 23 wherein the selecting the full-scale value comprises selecting a minimum value from a set of values at which saturation of said reading circuit is not detected.

25. The method of claim 23 wherein the selecting the full-scale value comprises iteratively modifying a full-scale value of said reading circuit until an absence of saturation of said output signal is detected.

26. The method of claim 25 wherein said iteratively modifying comprises:

selecting a first full-scale value;

determining whether saturation of the reading circuit is present at the first full-scale value based on the output of the reading circuit; and

when it is determined that saturation of the reading circuit is present, incrementing the first full-scale value.

27. The method of claim 26 wherein said first full-scale value is one of:

a minimum selectable value and a default value.

28. The method of claim 23, comprising:

monitoring the output signal to detect saturation of the reading circuit; and

when saturation of the reading circuit is detected,

determining whether saturation is present at a largest selectable full-scale value; and

when it determined that saturation is not present at the largest selectable full-scale value, increment the selected full-scale value.

29. The method of claim 23, further comprising:

generating the electrical detection signal.

30. A system, comprising:

means for generating an output signal based on an electrical detection signal indicative of at least one characteristic of a magnetic field; and

means for selecting a full-scale value of said means for generating.

31. The system of claim 30, further comprising:

means for generating the electrical detection signal.

32. The system of claim 30, further comprising:

means for receiving the output signal.