Circuits and Methods for Processing a Signal Generated by a Plurality of Measuring Devices

• US 20120299588A1
• Filed: 05/23/2011
• Published: 11/29/2012
• Est. Priority Date: 05/23/2011
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Petrie, Craig S.
• Granted Patent: US 8,860,410 B2
• Time in Patent Office: Days
• US Class Current: 324/251
• CPC Class Codes: G01R 33/0029 Treating the measured signals, e.g. removing offset or noise
• CPC Class Codes: G01R 33/077 Vertical Hall-effect devices

Abstract

Circuits and methods use a feedback arrangement to select one or more measuring devices from a plurality of measuring devices in order to rapidly identify a direction of a sensed parameter. In some embodiments, the plurality of measuring devices corresponds to a plurality of magnetic field sensing elements and the sensed parameter is a magnetic field.

Claims

1. An electronic circuit, comprising:

a plurality of measuring devices to generate a corresponding plurality of measuring device signals, each one of the plurality of measuring device signals having a respective magnitude related to an angle of a direction of a sensed parameter;

a preprocessing circuit coupled to receive a signal representative of the plurality of measuring device signals, coupled to receive an index value identifying a selection of one or more measuring devices from among the plurality of measuring devices, and configured to generate either a first preprocessed output signal representative of a selected one or more of the plurality of measuring device signals selected in accordance with the index value or a second preprocessed output signal representative of a sum of a selected set of signals representative of the plurality of measuring device signals selected in accordance with the index value; and

a post processing circuit coupled to receive the first or the second preprocessed output signal and configured to relate a crossing of a predetermined value of the first or the second preprocessed output signal to the index value, wherein the crossing of the predetermined value is representative of the angle of the direction of the sensed parameter, wherein the post processing circuit comprises;

an analog-to-digital converter coupled to receive a signal representative of the first or the second preprocessed output signal and configured to generate a digital converted signal, wherein the digital converted signal corresponds to the index value.

2. The circuit of claim 1, further comprising:

an integrator coupled to receive the first or the second preprocessed output signal and configured to generate an integrated signal, wherein the analog-to-digital converter is coupled to receive the integrated signal and configured to generate the digital converted signal in accordance with the integrated signal.

3. The circuit of claim 2, wherein the post processing circuit further comprises a digital filter coupled to receive the digital converted signal and configured to filter the digital converted signal to provide a digital filtered signal representative of the angle of the direction of the sensed parameter.

4. The circuit of claim 3, wherein the digital filter comprises a decimation filter.

5. The circuit of claim 2, wherein the post processing circuit further comprises:

a count circuit coupled to receive the digital converted signal and configured to generate first and second count values corresponding to counts of a number of occurrences of a zero and a one, respectively, in the least significant bit of the digital converted signal within a time period; and

a comparison circuit configured to compare the first count value to the second count value and configured to generate a count comparison value representative of the angle of the direction of the sensed parameter.

6. The circuit of claim 1, further comprising:

an integrator coupled to receive the first or the second preprocessed output signal and configured to generate an integrated signal, wherein the analog-to-digital converter is coupled to receive the integrated signal and configured to generate the digital converted signal as a multi-bit digital converted signal in accordance with the integrated signal; and

a modulo circuit coupled to receive the multi-bit digital converted signal, configured to add or subtract a predetermined value to or from the multi-bit digital converted signal depending upon whether the multi-bit digital converted signal is below or above a predetermined value range, respectively, and configured to generate a multi-bit digital modulo signal, wherein the multi-bit digital modulo signal corresponds to the index value.

7. The circuit of claim 6, wherein the post processing circuit further comprises a digital filter coupled to receive the digital multi-bit modulo signal and configured to filter the digital multi-bit modulo signal to provide a digital filtered signal representative of the angle of the direction of the sensed parameter.

8. The circuit of claim 7, wherein the digital filter comprises a decimation filter.

9. The circuit of claim 1, wherein the plurality of measuring devices comprises a plurality of vertical Hall elements arranged in a circular vertical Hall element (CVH) structure over a common implant region in a common substrate, and wherein the sensed parameter is a magnetic field.

10. The circuit of claim 9, further comprising

an integrator coupled to receive the first or the second preprocessed output signal and configured to generate an integrated signal, wherein the analog-to-digital converter is coupled to receive the integrated signal and configured to generate the digital converted signal in accordance with the integrated signal.

13. The circuit of claim 9, further comprising:

an integrator coupled to receive the first or the second preprocessed output signal and configured to generate an integrated signal, wherein the analog-to-digital converter is coupled to receive the integrated signal and configured to generate the digital converted signal as a multi-bit digital converted signal in accordance with the integrated signal; and

a modulo circuit coupled to receive the multi-bit digital converted signal, configured to add or subtract a predetermined value to or from the multi-bit digital converted signal depending upon whether the multi-bit digital converted signal is below or above a predetermined value range, respectively, and configured to generate a multi-bit digital modulo signal, wherein the multi-bit digital modulo signal corresponds to the index value.

14. The circuit of claim 13, wherein the post processing circuit further comprises a digital filter coupled to receive the digital multi-bit modulo signal and configured to filter the multi-bit digital modulo signal to provide a digital filtered signal representative of the angle of the direction of the magnetic field.

15. The circuit of claim 14, wherein the digital filter comprises a decimation filter.

16. The circuit of claim 1, wherein the plurality of measuring devices comprises a plurality of magnetic field sensing elements, and wherein the sensed parameter is a magnetic field.

17. The circuit of claim 16, wherein the circuit is disposed upon a common substrate, and wherein the plurality of measuring device signals is responsive to an angle of a direction of a magnetic field.

18. The circuit of claim 16, wherein the plurality of measuring devices comprises a plurality of vertical Hall elements disposed on the common substrate.

11. The circuit of claim 11, wherein the post processing circuit further comprises a digital filter coupled to receive the digital converted signal and configured to filter the digital converted signal to provide a digital filtered signal representative of the angle of the direction of the magnetic field.

12. The circuit of claim 11, wherein the digital filter comprises a decimation filter.

19. A method of processing a plurality of measuring device signals generated by a plurality of measuring devices, comprising:

receiving a signal representative of the plurality measuring device signals, each one of the plurality of measuring device signals having a respective magnitude related to an angle of a direction of a sensed parameter;

receiving an index value identifying a selection of one or more measuring devices from among the plurality of measuring devices;

generating either a first preprocessed output signal representative of a selected one or more of the plurality of measuring device signals selected in accordance with the index value or a second preprocessed output signal representative of a sum of a selected set of signals representative of the plurality of measuring device signals selected in accordance with the index value; and

relating a crossing of a predetermined value of the first or the second preprocessed output signal to the index value, wherein the crossing of a predetermined value is representative of the angle of the direction of the sensed parameter, wherein the relating comprises;

converting a signal representative of the first or the second preprocessed output signal with an analog-to-digital converter to generate a digital converted signal, wherein the digital converted signal corresponds to the index value; and

feeding back the index value to the step of receiving the index value.

20. The method of claim 19, further comprising:

integrating the first or the second preprocessed output signal to generate an integrated signal, wherein the converting comprises;

converting the integrated signal to generate the digital converted signal.

21. The method of claim 20, further comprising digital filtering the digital converted signal to provide a digital filtered signal representative of the angle of the direction of the sensed parameter.

22. The method of claim 21, wherein the digital filtering comprises decimating.

23. The method of claim 20, further comprising:

generating a first count value corresponding to a count of a number of occurrences of a zero in the least significant bit of the digital converted signal within a time period;

generating a second count value corresponding to a count of a number of occurrences of a one in the least significant bit of the digital converted signal within the time period; and

comparing the first count value to the second count value to generate a count comparison value representative of the angle of the direction of the sensed parameter.

24. The method of claim 19, further comprising:

integrating the first or the second preprocessed output signal to generate an integrated signal, wherein the converting comprises converting the integrated signal to generate the digital converted signal as a multi-bit digital converted signal; and

adding or subtracting a predetermined value to or from the digital multi-bit converted signal depending upon whether the multi-bit digital converted signal is below or above a predetermined value range, respectively, generate a multi-bit digital modulo signal, wherein the multi-bit digital modulo signal corresponds to the index value.

25. The method of claim 24, further comprising digital filtering the multi-bit digital modulo signal to provide a digital filtered signal representative of the angle of the direction of the sensed parameter.

26. The method of claim 25, wherein the digital filtering comprises decimating.

27. The method of claim 19, wherein the plurality of measuring devices comprises a plurality of vertical Hall elements arranged in a circular vertical Hall element (CVH) structure over a common implant region in a common substrate, and wherein the sensed parameter is a magnetic field.

28. The method of claim 27, further comprising:

integrating the first or the second preprocessed output signal to generate an integrated signal, wherein the converting comprises;

converting the integrated signal to generate the digital converted signal.

29. The method of claim 28, further comprising digital filtering the digital converted signal to provide a digital filtered signal representative of the angle of the direction of the magnetic field.

30. The method of claim 28, wherein the digital filtering comprises decimating.

31. The method of claim 27, further comprising:

integrating the first or the second preprocessed output signal to generate an integrated signal, wherein the converting comprises converting the integrated signal to generate the digital converted signal as a multi-bit digital converted signal; and

adding or subtracting a predetermined value to or from the digital multi-bit converted signal depending upon whether the multi-bit digital converted signal is below or above a predetermined value range, respectively, to generate a multi-bit digital modulo signal, wherein the multi-bit digital modulo signal corresponds to the index value.

32. The method of claim 31, further comprising digital filtering the digital multi-bit modulo signal to provide a digital filtered signal representative of the angle of the direction of the magnetic field.

33. The method of claim 31, wherein the digital filtering comprises decimating.

34. The method of claim 19, wherein the plurality of measuring devices comprises a plurality of magnetic field sensing elements, and wherein the sensed parameter is a magnetic field.

35. The method of claim 34, wherein the plurality of measuring devices comprises a plurality of vertical Hall elements disposed on the common substrate.