Motion sensor, method, and computer-readable storage medium providing a motion sensor that adjusts gains of two circuit channels to bring the gains close to each other

• US 8,680,848 B2
• Filed: 06/03/2010
• Issued: 03/25/2014
• Est. Priority Date: 06/03/2010
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Foletto, Andrea, Fernandez, Devon, Burdette, Eric
• Primary Examiner(s): PATIDAR, JAY M
• Application Number:
  US12/793,163
• Publication Number:
  US 20110298448A1
• Time in Patent Office: 1,391 Days
• Field of Search: 324/207.2, 324/207.21, 324/207.25, 324173-174, 324/207.12, 324/207.15
• US Class Current: 324/207.25
• CPC Class Codes: G01D 5/14 influencing the magnitude of a current or voltage
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01D 5/2448 Correction of gain, threshold, offset or phase control
• CPC Class Codes: G01P 21/00 Testing or calibrating of apparatus or devices covered by the preceding groups
• CPC Class Codes: G01P 3/487 delivered by rotating magnets
• CPC Class Codes: G01P 3/488 delivered by variable reluctance detectors
• CPC Class Codes: G01P 3/489 Digital circuits therefor

Abstract

A motion sensor includes an amplitude difference processor coupled to receive a first signal representative of a first one of a plurality of AGC control signals and a second signal representative of a second one of the plurality of AGC control signals. The amplitude difference processor is configured to detect if a value of the first signal is representative of a different gain than a value of the second signal by a predetermined amount. In response to the detection, the AGC processor is configured to change the value of the first one of the plurality of AGC control signals to bring its value closer to the value of the second one of the AGC control signals. A method and computer-readable storage medium can use the motion sensor.

Claims

1. A motion sensor, comprising:

a plurality of magnetic field sensing elements configured to generate a plurality of magnetic field signals indicative of a magnetic field associated with an object;

a plurality of AGC circuits coupled to receive a respective plurality of signals representative of the plurality of magnetic field signals and configured to generate a respective plurality of gain-adjusted output signals;

an AGC processor configured to generate a plurality of AGC control signals to control respective gains of the plurality of AGC circuits; and

a channel amplitude difference processor coupled to receive a first signal representative of a first one of the plurality of AGC control signals and a second signal representative of a second one of the plurality of AGC control signals, wherein the channel amplitude difference processor is configured to detect if a value of the first signal is representative of a different gain than a value of the second signal by a predetermined amount, and configured to generate an AMP_DIFF_FLAG signal indicative of the different gain in response to the detection, wherein, in response to the AMP_DIFF_FLAG signal, the AGC processor is configured to change the value of the first one of the plurality of AGC control signals to bring its value closer to the value of the second one of the AGC control signals.

2. The motion sensor of claim 1, wherein the channel amplitude difference processor is further configured to identify positive and negative peaks of the first one of the plurality of gain-adjusted output signals, wherein the AGC processor is configured to change the value of the first one of the plurality of AGC control signals to bring its value closer to the value of the second one of the AGC control signals only if an identified positive or negative peak of the first one of the plurality of gain-adjusted output signal is a predetermined peak.

3. The motion sensor of claim 2, wherein the predetermined peak is a first peak in time following a time when power is first applied to the motion sensor.

4. The motion sensor of claim 3, wherein the channel amplitude difference processor is further configured to generate a LEARN amplitude window having a higher limit and a lower limit and to identify the first peak as occurring before the first one of the gain-adjusted output signals crosses at least one of the higher limit or the lower limit.

5. The motion sensor of claim 4, wherein the channel amplitude difference processor is configured to identify the first peak as occurring before the first one of the gain-adjusted output signals crosses both the higher limit and the lower limit.

6. The motion sensor of claim 4, further comprising a plurality of AOA circuits coupled to receive another respective plurality of signals representative of the plurality of magnetic field signals and configured to generate a respective plurality of offset-adjusted output signals, wherein the motion sensor further comprises an AOA processor configured to generate a plurality of AOA control signals to control respective DC offsets of the plurality of AOA circuits, wherein each one of the AOA circuits is coupled in series with a respective one of the plurality of AGC circuits.

7. The motion sensor of claim 1, wherein the channel amplitude difference processor is further configured to identify cycles of at least one of the plurality of magnetic field signals, wherein the AGC processor is further configured to change the value of the first one of the plurality of AGC control signals to bring its value closer to the value of the second one of the AGC control signals only if the an identified cycle is a predetermined cycle.

8. The motion sensor of claim 7, wherein the predetermined cycle is a first cycle in time following a time when power is first applied to the motion sensor.

9. A method of detecting a motion of an object, comprising:

generating a plurality of magnetic field signals indicative of a magnetic field associated with the object;

generating a plurality of gain-adjusted signals representative of the plurality of magnetic field signals;

generating a plurality of AGC control signals to control respective gains of the plurality of gain-adjusted output signals;

detecting if a value of a first one of the plurality of AGC control signals is representative of a higher gain than a value of a second one of the plurality of AGC control signals by a predetermined amount; and

in response to the detecting, changing the value of the first one of the plurality of AGC control signals to bring its value closer to the value of the second one of the AGC control signals.

10. The method of claim 9, wherein the changing the value comprises:

identifying positive and negative peaks of a first one of the plurality of gain-adjusted signals; and

changing the value of the first one of the plurality of AGC control signals to bring its value closer to the value of the second one of the AGC control signals only if an identified positive or negative peak of the first one of the plurality of gain-adjusted signal is a predetermined peak.

11. The method of claim 10, wherein the identifying positive and negative peaks comprises identifying a first peak in time following a time when power is first applied to the motion sensor.

12. The method of claim 11, wherein the identifying the first peak comprises:

generating a LEARN amplitude window having a higher limit and a lower limit; and

identifying the first peak as occurring before the first one of the gain-adjusted signals crosses at least one of the higher limit or the lower limit.

13. The method of claim 12, wherein identifying the first peak comprises:

identifying the first peak as occurring before the first one of the gain-adjusted signals crosses both the higher limit and the lower limit.

14. The method of claim 12, further comprising:

generating a plurality of offset-adjusted signals representative of the plurality of magnetic field signals; and

generating a plurality of AOA control signals to control respective DC offsets of the plurality of offset-adjusted signals.

15. The method of claim 9, further comprising:

identifying cycles of at least one of the plurality of magnetic field signals; and

changing the value of the first one of the plurality of AGC control signals to bring its value closer to the value of the second one of the AGC control signals only if the an identified cycle is a predetermined cycle.

16. The method of claim 15, wherein the identified cycle is a first cycle in time following a time when power is first applied to the motion sensor.

17. A non-transitory computer-readable storage medium having computer readable code thereon for providing sensing of a motion of an object, the medium comprising:

instructions for receiving a plurality of magnetic field signals indicative of a magnetic field associated with the object;

instructions for generating a plurality of gain-adjusted signals representative of the plurality of magnetic field signals;

instructions for generating a plurality of AGC control signals to control respective gains of the plurality of gain-adjusted output signals;

instructions for detecting if a value of a first one of the plurality of AGC control signals is representative of a higher gain than a value of a second one of the plurality of AGC control signals by a predetermined amount; and

instructions for, in response to the detecting, changing the value of the first one of the plurality of AGC control signals to bring its value closer to the value of the second one of the AGC control signals.

18. The non-transitory computer-readable storage medium of claim 17, wherein the instructions for changing the value comprise:

instructions for identifying positive and negative peaks of a first one of the plurality of gain-adjusted signals; and

instructions for changing the value of the first one of the plurality of AGC control signals to bring its value closer to the value of the second one of the AGC control signals only if an identified positive or negative peak of the first one of the plurality of gain-adjusted signal is a predetermined peak.

19. The non-transitory computer-readable storage medium of claim 18, wherein the instructions for identifying positive and negative peaks comprise instructions for identifying a first peak in time following a time when power is first applied to the motion sensor.

20. The non-transitory computer-readable storage medium of claim 19, wherein the instructions for identifying the first peak comprise:

instructions for generating a LEARN amplitude window having a higher limit and a lower limit; and

instructions for identifying the first peak as occurring before the first one of the gain-adjusted signals crosses at least one of the higher limit or the lower limit.

21. The non-transitory computer-readable storage medium of claim 20, wherein instructions for identifying the first peak comprise:

instructions for identifying the first peak as occurring before the first one of the gain-adjusted signals crosses both the higher limit and the lower limit.

22. The non-transitory computer-readable storage medium of claim 20, further comprising:

instructions for generating a plurality of offset-adjusted signals representative of the plurality of magnetic field signals; and

instructions for generating a plurality of AOA control signals to control respective DC offsets of the plurality of offset-adjusted signals.

23. The non-transitory computer-readable storage medium of claim 17, further comprising:

instructions for identifying cycles of at least one of the plurality of magnetic field signals; and

instructions for changing the value of the first one of the plurality of AGC control signals to bring its value closer to the value of the second one of the AGC control signals only if the an identified cycle is a predetermined cycle.

24. The non-transitory computer-readable storage medium of claim 23, wherein the identified cycle is a first cycle in time following a time when power is first applied to the motion sensor.