Hall Sensor Readout System with Offset Determination Using the Hall Element Itself

Patent metadata

Field	Value
Publication number	US-2016252589-A1
Application number	US-201415034738-A
Country	US
Kind code	A1
Filing date	Nov 6, 2014
Priority date	Nov 6, 2013
Publication date	Sep 1, 2016
Grant date	—

Abstract

A method for providing offset compensation in a Hall sensor comprising at least one Hall element having a plate-shaped sensor element made of a doped semiconductor material, comprises using measurements on the Hall element itself. The method comprises obtaining a first readout signal (V H ) from the at least one Hall element which is substantially dependent on the magnetic field, obtaining a second readout signal (V P ) from the at least one Hall element which is substantially independent of the magnetic field, and using the second readout signal (V P ) for obtaining a prediction ({circumflex over (V)} O ) of the offset (V O ) on the first readout signal (V H ).

First claim

1 - 28 . (canceled)

29 . Method for offset determination in a Hall sensor for measuring a magnetic field,
the Hall sensor comprising: at least one Hall element having a plate-shaped sensor element made of a doped semiconductor material, the Hall sensor being embedded in a semiconductor chip further comprising storage means storing on-chip, in a non-volatile form, calibration data obtained from a calibration procedure, the method comprising: i) obtaining a first readout signal (V H ) from the at least one Hall element by using a first technique which yields a result that is substantially dependent on the magnetic field to be measured including an offset (V O ) to be determined, ii) obtaining a second readout signal (V P ) from the at least one Hall element by using a second technique which yields a result that is substantially independent of the magnetic field but is correlated to said offset (V O ), and iii) using the second readout signal (V P ) for obtaining a prediction ({circumflex over (V)} O ) of the offset (V O ) on the first readout signal (V H ) as a linear function of the second readout signal (V P ), expressed as {circumflex over (V)} O =a+b V P , a and b being parameters in the linear function based on the calibration data stored in the on-chip storage means.

30 . Method according to claim 29 , wherein the parameters a and b in the offset prediction ({circumflex over (V)} O ) are temperature dependent.

31 . Method according to claim 29 , wherein the parameters a and/or b in the linear function expressing the offset prediction ({circumflex over (V)} O ) in function of the second readout signal (V P ) are optimised by means of a calibration procedure.

32 . Method according to claim 31 , wherein the calibration procedure comprises the steps of:
bringing the Hall sensor in an environment with a known magnetic field and at a known temperature (T) selected from a first set of temperatures, and recording, for each temperature (T) of the first set of temperatures, the first readout signal (V H ) obtained by using the first technique as a first reference signal (V Oref (T)), and the second readout signal (V P ) obtained by using the second technique as a second reference signal (V Pref (T)).

33 . Method according to claim 32 , further comprising determining the parameter b by means of a calibration procedure comprising the steps of:
bringing the Hall sensor in an environment with known magnetic field and at a known temperature selected from a second set of temperatures, and recording, for each temperature of the second set of temperatures, the first readout signal (V H ) obtained by using the first technique as a third reference signal (V Osec (T)), and the second readout signal (V P ) obtained by using the second technique as a fourth reference signal (V Psec (T)), and determining the parameter b from the recorded reference signals as a scale factor between (V Osec −V Oref ) and (V Psec −V Pref ), with the assumption that the reference signals are interpolated when they need to be determined at a temperature for which no direct measurement is available.

34 . Method according to claim 32 , wherein the offset prediction ({circumflex over (V)} O ) is determined from the measured second readout signal (V P ) and from the recorded reference signals as:
{circumflex over (V)} O =V Oref ( T )+ b ·( T )( V P −V Pref ( T ))

35 . Method according to claim 29 , wherein obtaining the second readout signal (V P ) from the at least one Hall element of step ii) comprises making linear combinations of readout signals with at least two Hall-type measurements, so that the magnetic field component is cancelled out.

36 . Method according to claim 29 ,
wherein obtaining the second readout signal (V P ) from the at least one Hall element of step ii) comprises readout of a configuration comprising at least two neighbouring Hall elements which are interconnected such that the magnetic field components of the individual Hall elements cancel one another out; and optionally wherein obtaining the second readout signal (V P ) from the at least one Hall element of step ii) comprises averaging of measurement signals obtained from geometric spinning measurements on a plurality of neighbouring Hall elements.

37 . Method according to claim 29 , at least one Hall element comprising at least four nodes, wherein obtaining a second readout signal (V P ) from the at least one Hall element of step ii) comprises obtaining measurement signals in a Van der Pauw-type measurement set-up of the Hall element wherein nodes that have a same function appear consecutive when going over the nodes in an order defined by following the edge of the plate-shaped sensor element, the second readout signal (V P ) being obtained by differencing two Van der Pauw-type measurements on the at least one Hall element.

38 . Method according to claim 37 ,
wherein either differencing two Van der Pauw-type measurements includes differencing two Van der Pauw measurements obtained sequentially; or wherein differencing two Van der Pauw-type measurements is obtained by performing a single measurement on an interconnection of at least two Hall plates.

39 . Method according to claim 37 , wherein obtaining a second readout signal (V P ) from the at least one Hall element of step ii) comprises taking a linear combination of a plurality of Van der Pauw-type measurements on the at least one Hall element.

40 . Method according to claim 29 , wherein obtaining the second readout signal (V P ) from the at least one Hall element of step ii) comprises making linear combinations of readout signals with at least two Hall-type measurements, in such a way that the magnetic field component is cancelled out, and/or comprises at least one Van der Pauw type measurement.

41 . Method according to claim 29 ,
furthermore comprising measuring the actual temperature (Ta) and using this actual temperature (Ta) in the offset prediction; and/or further comprising the step of iv) removing the offset prediction ({circumflex over (V)} O ) from the first readout signal (V H ) to compensate the offset (V O ).

42 . A semiconductor chip comprising a Hall sensor, the Hall sensor comprising:
at least one Hall element, each Hall element having a plate-shaped sensor element made of a doped semiconductor material, storage means storing on-chip, in a non-volatile form, calibration data obtained from a calibration procedure; sensor means for obtaining a first readout signal (V H ) from the at least one Hall element using a first technique that yields a result which is substantially dependent on the magnetic field and has an offset (V O ) to be determined, sensor means for obtaining a second readout signal (V P ) from the at least one Hall element using a second technique that yields a result which is substantially independent of the magnetic field but is correlated to said offset (V O ), and means for obtaining a prediction ({circumflex over (V)} O ) of the offset (V O ) on the first readout signal (V H ) as a linear function of the second readout signal (V P ), expressed as {circumflex over (V)} O =a+b V P , a and b being parameters in the linear function based on the calibration data stored in the on-chip storage means, means for compensating the offset (V O ) on the first readout signal (V H ) based on the prediction signal ({circumflex over (V)} O ).

43 . Semiconductor device according to claim 42 , wherein the means for compensating the offset (V O ) comprises a controlled source for compensating offset on the first readout signal (V H ), the control

Assignees

• Melexis Technologies Nv

Inventors

• Raman Johan
• Rombouts Pieter

Classifications

• G01R33/0035 Primary

  Calibration of single magnetic sensors, e.g. integrated calibration · CPC title

• G01R33/0029

  Treating the measured signals, e.g. removing offset or noise · CPC title

• G01R33/07

  Hall effect devices · CPC title

• G01R33/0082

  Compensation, e.g. compensating for temperature changes · CPC title

• G01R33/075

  Hall devices configured for spinning current measurements · CPC title