FIELD OF THE INVENTION:
The present invention relates to Hall sensors for detecting spatial components of
a magnetic field at a reference point, as well as to calibration and measurement
methods used therein.
BACKGROUND OF THE INVENTION:
Apart from measuring magnetic fields with regard to amount and direction, Hall
sensor elements based on the Hall-Effect are frequently used in the art, for
contactless touchless signal generators for wearless detection of the position of
switches or actuators. A further possible field of application is current
measurement, wherein a Hall sensor element is positioned close to a conductive
trace and measures the current in the conductive trace in a contactless manner
by detecting the magnetic field generated by the current in the conductive trace.
In practical application, Hall sensor elements have particularly shown to be
useful due to their relatively strong insensitivity against outside influence, such
as contamination, etc.
In the art, both the so-called horizontal or lateral Hall sensor elements and
vertical sensor elements are known, wherein Fig. 9a exemplarily shows a
horizontal Hall sensor element and Fig. 9b a vertical Hall sensor element
according to the prior art.
Generally, a Hall sensor element consists of a semiconductor die having four
contact terminals provided for electrical connection to an external control circuit.
Of the four contact terminals of a Hall sensor element, two contact terminals are
provided for operating current impression by an active semiconductor region,
while the other two contact terminals are provided for detecting the Hall voltage.

If the operating current-carrying semiconductor die is exposed to a magnetic
field having the induction 6, a deviation of the current paths results, which is
caused by the "Lorenz force" acting on the moving charge carriers in the
magnetic field. The Hall voltage results perpendicular to the direction of the
current flow and perpendicular to the applied magnetic field in the active
semiconductor region.
As basically shown in Fig. 9a, a horizontal Hall sensor element 900
according to the prior art generally consists of an n-doped semiconductor
region 902 on a p-doped semiconductor substrate 904. A Hall sensor
element arranged in parallel to a chip surface (x-y-Level) is referred to
as horizontal.
The n-doped active region 902 is normally connected to an external control or
evaluation logic, respectively, via four contact electrodes 906a-d arranged in the
active region 902 in opposing pairs.
EP 1 637 898 A1 discloses a one-dimensional magnetic field sensor
calibratable via a reference field. Thereby, a reference field generator
generates a magnetic alternating field differing significantly in frequency
from a measurement field. A downstream signal processing allows a
calibration of the sensor or a compensation of temperature effects,
respectively, by separating the measurement or reference field
components, respectively, in the frequency domain. A horizontal magnetic
field sensor, a so-called Hall die, is used as magnetic field sensor.
OBJECTS & SUMMARY OF THE INVENTION:
This object is solved by a magnetic field sensor calibratable during
measurement operation and a method for calibrating a magnetic field

field sensor during a measurement operation.
The present invention provides a magnetic field sensor calibratable during
a measurement operation for detecting first, second, and third spatial
components Bz, By, and Bx of a magnetic field at a reference point,
wherein the magnetic field has first, second, and third measurement field
components BMz, BMy, BMx and first, second and third calibration field
components BKz/ BKy, and BKx, comprising a first sensor element
arrangement for detecting the first magnetic field component Bz having a
first measurement field component BMz and a first calibration field
component BKZ with respect to a first spatial axis z at the reference point.
Further, the magnetic field sensor comprises a second sensor element
arrangement for detecting the second magnetic field component By having
a second measurement field component BMy and a second calibration
field component BKy, with respect to a second spatial axis y at reference
point, and a third sensor element arrangement for detecting the third
magnetic field component Bx, having a third measurement field component
BMx and a third calibration field component B«xr with respect to a third
spatial axis x at the reference point. Further, the magnetic field sensor
has an excitation line, which is arranged such with respect to the first,
second and third sensor element arrangements, that when impressing a
predetermined current into the excitation line, a first predetermined
calibration field component B^ with respect to the first spatial axis z in
the first sensor element arrangement is generated, a second
predetermined calibration field component BKy with respect to the second
spatial axis y in the second sensor element arrangement is generated, and
a third predetermined calibration field component BKX with respect to the
third spatial axis x in the third sensor element arrangement is generated
generated, wherein the three spatial axes z, y, x run along linearly
independent position vectors.

The object is further solved by a method for calibrating a magnetic field
sensor during measurement operation by detecting first, second, and third
spatial components Bz, By, and By of a magnetic field at a reference point,
wherein the magnetic field has first, second, and third measurement field
components BMz, BMy, and BMx and a first, second, and a third calibration
field component B^, BKy, and BKX, comprising a step of detecting the first
magnetic field component Bx having a first measurement field component
BMZ and a first calibration field component B^, with respect to the first
spatial axis z at the reference point, and of detecting the second magnetic
field component By, having a second measurement field component BMy
and a second calibration field component BKy, with respect to the second
spatial axis y at the reference point. The method further comprises a step
of detecting the third magnetic field component Bx, having a third
measurement field component BMX and a third calibration field component
BKX, with respect to the third spatial axis x at the referent point, and a
step of generating the first, second, and third calibration field components
BKZ/ BKy, and BKX with respect to the first, second and third spatial axes z,
y, 5 and x, wherein the first, second and third spatial axes runs along
linearly independent position vectors.
The present invention is based on the knowledge that a spatial
arrangement of different magnetic field sensors, preferably symmetrically
in pairs, which detect the components of a magnetic field at one point,
and which can be operated with a compensation method, such as the
spinning-current-method, offers the possibility to calibrate the same
during operation by applying a calibration field caused by a single

excitation line. The inventive magnetic field sensor can be simultaneously
in a measurement field and a calibration field, and can be operated in a
measurement method consisting of several measurement phases,
preferably spinning-current.
A first combination of the measurement results of the individual phases
allows the extraction of a measurement component originating from the
magnetic field to be measured, and in which both components originating
from the calibration field and components originating from device
tolerances are substantially eliminated. Further, a second combination of
the measurement results of the individual measurement phases allows the
extraction of a measurement component originating from the calibration
field and in which components of the magnetic field to be measured are
substantially eliminated.
The inventive magnetic field sensor and the inventive method have the
advantage that no additional measurement phases are required for
calibration when using conventional compensation methods, such as the
spinning current method.
An excitation line, which generates calibration field components in all
spatial directions due to its geometry is powered, i.e. the calibration field
is directed such that the two combinations of the measurement results
from the individual measurement phases are enabled in the described
way. Thus, generation and direction of the calibration field is adapted to
the measurement phases of the compensation method or integrated in the
same, respectively. This has the advantage that the arrangement needs
only a single excitation line, which results in the inventive magnetic field
sensor providing simple and uncomplicated test options. The excitation

lines of several inventive magnetic field sensors can, for example, be
cascaded and thus be tested together in an on-wafer-test.
It is a further advantage of the inventive magnetic field sensor and
method that the magnetic field sensor can be calibrated during operation
and that no additional hardware or time effort is required. For example,
the measurement results of the individual measurement phases can be
combined or evaluated, respectively, by a micro-controller or a processor,
so that the additional effort is limited to one additional computation
operation. The measurement field components and the calibration field
components can each be provided simultaneously and in a compensated
manner. This is particularly advantageous in security critical applications,
for example, such as in the automobile industry or medical technology,
since the magnetic field sensor can be continuously calibrated or
adjusted, respectively, and its functionality can simultaneously be
monitored without having to make compromises with regard to the quality
or quantity of a measurement.
Preferred embodiments of the invention will be discussed below with
reference to the accompanying drawings.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS:
Fig. 1 a schematic arrangement of Hall sensor elements according
to an embodiment of the magnetic field sensor calibratable
during measurement operation according to the present
invention;
Fig. 2 a sectional view with schematic magnetic field lines for
illustrating the calibration method in the embodiment of the
inventive magnetic field sensor;

Fig. 3 a schematic arrangement of Hall sensor elements according
to a further inventive embodiment;
Fig. 4a-d schematic wirings and equivalent diagrams of Hall sensor
elements in an embodiment for illustrating the inventive
compensation method;
Fig. 5 an alternative arrangement of the Hall sensor elements
according to a further embodiment of the inventive magnetic
field sensor;
Fig. 6 a schematic arrangement of the Hall sensor elements
according to a further embodiment for illustrating the
calibration method;
Fig. 7 a schematic arrangement for illustrating the calibration
method according to a further embodiment;
Fig. 8 an embodiment of an arrangement of several sensor elements
for detecting a spatial magnetic field component;
Fig. 9a the schematic structure of a horizontal Hall sensor element
according to the prior art;
Fig. 9b the schematic structure of a vertical Hall sensor element
according to the prior art;
Fig. 12 a schematic arrangement of individual Hall sensor elements
for detecting a spatial magnetic field at one point.

DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENT OF THE INVENTION:
With regard to the following discussion, it should be considered that equal
or similar functional elements in the different embodiments have the same
reference numbers and are thus interchangeable in the different
embodiments illustrated below.
The inventive structure of a magnetic field sensor 100 calibratable during
operation according to a first embodiment will be discussed with reference
to Fig. 1. Fig. 1 shows an embodiment of an inventive magnetic field
sensor 100 for detecting a magnetic field at a reference point 101.
Further, Fig. 1 shows a first sensor element arrangement 102, a second
sensor element arrangement 104, and a third sensor element
arrangement 106. Further, an excitation line 108 is illustrated in Fig. 1.
The magnetic field sensor can, for example, be implemented on a
substrate whole main surface runs parallel to the x-y-level of the
arrangement, wherein the z-component runs perpendicular thereto.
Correspondingly, the magnetic field is divided into three components Bz,
By and Bx, each composed of a measurement field component BMz, BMy,
and BMx, and a calibration field component BKz, BKy and BKx-
As illustrated in Fig. 1, for detecting the first, second, and third spatial
components Bz, By and Bx of a magnetic field with the flow densitygat a
reference point 101, the magnetic field sensor 100 comprises the first
sensor element arrangement 102 for detecting the first magnetic field
component Bz having the first measurement field component BMz and a
first calibration field component BKz with respect to a first spatial axis z at
the reference point 101. In one embodiment, the sensor element

arrangement 102 is preferably realized by a horizontal Hall sensor
element whose measurement point is at the reference point 101.
Further, the magnetic field sensor 100 comprises the second sensor
element arrangement 104 for detecting the second magnetic field
component By having the second measurement field component BMy and
the second calibration field component B«y with respect to the second
spatial axis y at the reference point 101. In one embodiment, the sensor
element arrangement 104 is preferably realized by an arrangement of
several vertical Hall sensor elements that are arranged in pairs
symmetrical to the reference point 101. Further, the magnetic field sensor
100 comprises the third sensor element arrangement 106 for detecting
the third magnetic field component Bx having the third measurement field
component BMx and the third calibration field component BKX with respect
to the third spatial axis x at the reference point 101. In one embodiment,
the sensor element arrangement 106 is preferably realized by an
arrangement of several vertical Hall sensor elements that are arranged in
pairs symmetrical to the reference point 101.
The excitation line 108 of the magnetic field sensor 100 is preferably
arranged with respect to the first 102, second 104, and third 106 sensor
arrangements such that when impressing a predetermined current into the
excitation line 108, the first predetermined calibration field component B^
with respect to the first spatial axis z in the first sensor element
arrangement 102 is generated, the second predetermined calibration field
component BKy with respect to the second spatial axis y in the second
sensor element 5 arrangement 104 is generated, and the third
predetermined calibration field component BKx with respect to the third
spatial axis x in the third sensor element arrangement 106 is generated,

wherein the three spatial axes z, y, and x run along linearly independent
position vectors.
In the embodiment of Fig. 1, the position vectors of the three spatial axes
z, y, and x run orthogonally, and the three sensor element arrangements
detect the magnetic field according to its orthogonal components Bz=BMz +
BKZ, By=BMy+BKy und BX=BMX+BKX. For simplicity reasons, it is assumed here
and in the following description that the magnetic field is detected by
orthogonally arranged sensor element arrangements according to its
components Bz, By, and Bx. In other embodiments of the present invention,
the sensor elements can be basically arranged in any direction, as long as
they can fully detect the spatial components of the measurement field.
For illustrating the generation of the calibration field components BKz, BKy,
and BKx, Fig. 2 shows a cross-section of the magnetic field sensor 100. In
the cross-section illustrated in Fig. 2, the first sensor element
arrangement 102 can be seen in the center, as well as a cross-section
through the second sensor element arrangement 106, the cross-sections
of which can each be seen to the left and right of the first sensor element
arrangement 102. Above the second sensor element arrangement 106,
with respect to the main surface (x-y-level) of the substrate, runs the
excitation line 108. The geometry of the excitation line 108, i.e. its length
and dimensions, are selected such that due to a known impressed current,
a predetermined magnetic calibration flow density BKz, BKy, and BKx is
present that can be attributed to the excitation line 108. The calibration
flow density can be adjusted in a defined manner by the current IE and
the geometry or the properties, respectively, of the excitation line 108, i.e.
its height, width, thickness, material, relative position, etc., and the
sensor element arrangement can be calibrated by determining and
associating the associated Hall voltage. With the known magnetic

calibration flow densities, the Hall voltages generated thereby can be
associated and thus the magnetic field sensor can become calibratable.
In the illustrated embodiment, it is assumed that a current IE flows
through the excitation line, wherein in the crosssection illustrated in Fig.
2, the current is to flow into the arrangement through the right excitation
line 108, and is to flow out again on the left side through the excitation
line 108. The current flowing through the excitation line 108 generates a
magnetic field, whose field lines are indicated by concentric circles 200
around the excitation line 108 in Fig. 2. It can be seen that the sensor
element arrangement 102 is interspersed by all magnetic field lines 200 in
the same direction. Further, it can be seen that the cross-sections of the
sensor element arrangement illustrated in Fig. 2 are interspersed in the
opposite sense by the magnetic field lines 200. Analogously, this applies
for the third sensor element arrangement 104, which is not shown in Fig.
2 for clarity reasons, whose constellation is equivalent to the sensor
element arrangement 106. The pattern of the field lines 200, as well as
the orientation of the field lines 200 by which they intersperse the
individual sensor element arrangements, illustrates that a calibration of
the sensor element arrangement 102 is possible with the magnetic field
generated by the excitation line 108, while the calibration of the second
and third sensor element arrangements 104 and 106 requires
compensation of the oppositely acting field lines.
It can be seen from Fig. 2 that calibration of the magnetic field sensor
and detection of the measurement field can take place in different
operating phases, during which the excitation current can assume
different polarities (directions) and the sensor element arrangements
alternately provide Hall voltages. The first 102, second 104, and third
sensor element arrangements 106 can be operated in different operating

phases, wherein in every operating phase each of the first 102, second
104, and third sensor element arrangements 106 provides a measurement
signal attributed to the operating phase, wherein the measurement
signals attributed to the operating phases can be combined to a first total
measurement value by a first linear combination, such that the influence
of the measurement field components is reduced in the first total
measurement value, or the measurement signals attributed to the
operating phase can be combined to a second total measurement value by
a second linear combination, such that the influence of the calibration
field component is reduced in the second total measurement value. The
influence of the measurement field component or the calibration field
component, respectively, in the first or second total measurement value,
respectively, can be less than 10%, 1%, or 0.1% of the first or second
total measurement value. The operating phases and the detection of the
different calibration field or measurement field components, respectively,
will be discussed below with reference to a further preferred embodiment
and with reference to Figs. 3 and 4.
For this reason, a further preferred embodiment of the present invention
is illustrated in Fig. 3. Fig. 3 shows a preferred embodiment of the
inventive magnetic field sensor 100. Analogously, the magnetic field
sensor 100 comprises a first sensor element arrangement 102 around a
reference point 101, a second sensor element arrangement 104, and a
third sensor element arrangement 106. Further, the magnetic field sensor
100 comprises an excitation line 108. In the arrangement shown in Fig. 3,
the sensor element arrangements 104 and 106 each have four individual
sensor elements that are each arranged in pairs 104ab and 104cd, or
106ab and 106cd, respectively, symmetrical with respect 5 to the

reference point 101.
In the embodiment illustrated in Fig, 3, the sensor element arrangements
104 and 106 can be realized, for example, by an arrangement of vertical
Hall sensor elements. The second sensor element arrangement 104 in the
embodiment in Fig. 3 is composed of four individual sensor elements
104a-d, In the same manner, the third sensor element arrangement 106 is
composed of four preferably equal sensor elements 106a- d. The usage of
individual sensor elements, such as 104a-d and 106a-d allows wiring the
individual elements in a compensation wiring.
Fig. 4 illustrates an inventive wiring of the vertical individual elements and
discusses the principle of a compensation concept. Fig. 4al shows the
wiring of four vertical Hall sensor elements, for example, in the second
sensor element arrangement 104 with elements 104a-d. In the
arrangement shown in Fig. 4al, vertical 3-pin hole sensor elements are
used, which are preferably wired on one axis according to Fig. 3. Fig. 4al
shows two vertical Hall sensors element pairs 104ab and 104cd, wherein
the two sensor elements 104a and 104b form the sensor element pair
104ab, and the two sensor elements 104c and 104d form the sensor
element pair 104cd. In the considered embodiment, one vertical Hall
sensor element pair each forms a sensor for detecting a magnetic field
component that is arranged symmetrically around the reference point 101
according to Fig. 3. The sensor element pair 104ab and 104cd detects, for
example, the By component of the magnetic field.
The two vertical Hall sensor element pairs 104ab and 104cd are identically
structured such that that the structure can be discussed below based on the
vertical Hall sensor element pair 104ab. The same applies for the Hall sensor
element pairs 106ab and 106cd that then detect, for example, the B* component

of the magnetic field. The vertical Hall sensor element pair 104ab consists of two
vertical Hall sensor elements 104a and 104b.
Preferably, every vertical Hall sensor element has three contact areas, wherein in
the arrangement of the embodiment considered here, the external contacts 115
and 116, as well as the internal contacts 117 and 118 are electrically coupled to
each other, and the contacts 19 and 120 are implemented for detecting the Hall
voltage. Overall, as shown in Fig. 4al, four contact terminals TO-T3 result, by
which the two sensor element arrangements 104ab and 104cd are connected in
parallel. If a current IH is impressed between the contact terminals TO and T2, a
Hall voltage UH can be measured between the contact terminals Tl and T3 when
a magnetic field with the respective components is present, as illustrated in Fig.
4al.
The structure of the second vertical Hall sensor element pair 104cd is identical.
Only the contact terminals T0-T3 are shifted by one position with respect to the
vertical Hall sensor element pair 104ab, i.e. contacts 115 and 116 are coupled to
the terminal Tl, contacts 117 and 118 are coupled to terminal T3, contact 119 is
coupled to terminal T2, and contact 120 is coupled to terminal T4.
If a current is impressed between the contact terminals TO and T2 in the vertical
Hall sensor element pair 104cd, the arrangement functions as voltage divider and
no Hall voltage can be measured between the terminals Tl and T3. A bridge
voltage is only measureable between Tl and T3 when device tolerances or
inhomogenities, etc. occur. The same applies for the sensor element pair 106ab
and 106cd.
Fig. 4aII shows an electrical equivalent diagram of the Hall sensor
element pair arrangement of Fig. 4al. In Fig. 4al, for illustrative
purposes, the respective ohmic

resistances between the individual contact terminals TO and
T3 are shown by dotted lines. With regard to the first
vertical Hall sensor element pair 104ab, a resistance of
Rn results between the contact area 115 and the contact
area 119 connected to the contact terminal Tl, a resistance
of R12 between the contact terminal Tl and the contact area
117, a resistance of Rn between the contact area 118 and
the contact area connected to the contact terminal T3, and
a resistance of Ri4 between the contact area connected tc
the contact area T3 and the contact area 116. Analogously,
the equivalent resistors for the vertical Hall sensor
element pair 104cd are designated by R21, R22, R23/ and R24.
Fig. 4aII shows the electric equivalent diagram with a
parallel connection of the respective terminals T0-T3 of
the sensor element pairs 104ab and 104cd, which corresponds
to a Wheatstone-bridge. According to the wiring illustrated
in Fig. 4al and with the assumption that no magnetic field
is present and a voltage U is applied between the contact
terminals TO and T2, so that a current I is impressed, a
voltage of

results between the contact terminals Tl and T3 during a
first measurement phase, the measurement phase 0.
Fig. 4bl shows the wiring of the two vertical Hall sensor
element pairs 104ab and 104cd during measurement phase 1. A
current is impressed between the contact terminals Tl and
T3 across the voltage U, such that the vertical Hall sensor
element pair 104ab now functions as a voltage divider,
while the vertical Hall sensor element pair 104cd provides
a Hall voltage at the terminals tO, T2.

Fig. 4bII shows the electrical equivalent diagram of the
sensor element arrangement during the measurement phase 1
assuming that no magnetic field is present. For the
measurement phase 1, the following results between the
terminals TO and T2

Analogously, Fig. 4cl shows the arrangement during the
measurement phase 2. A current I is impressed across the
voltage U between the terminals T2 and TO, such that the
vertical Hall sensor element pair 104cd functions as
voltage divider during measurement phase 2, and the
vertical Hall sensor element pair 104ab is operated in
reverse polarity direction with respect to the measurement
phase 0.
Fig. 4cII shows the electrical equivalent diagram, again
assuming that no magnetic field exists. The following
results for this case between the terminals Tl and T3

Fig. 4dl shows the arrangement of the two vertical Hall
sensor element pairs 104ab and 104a during the measurement
phase 3. During the measurement phase 3, a current I is
impressed between the contact terminals T3 and Tl, such
that the vertical Hall sensor element pair 104ab functions
as voltage divider. Compared to the measurement phase 1,
the vertical Hall sensor element pair 104cd is operated in
reverse polarity direction. Fig. 4dII shows the electrical
equivalent diagram wherein the following results between
the terminals TO and T2


The equations 1-4 show that
and
this means that by adding the measured voltages from the
individual mass measurement phases possible offset voltages
can be compensated. This is also referred to as spinning
current, since the current feeding rotates across the
contact terminals. Thus, with the described method,
deviations resulting from device tolerances, such as
contaminations, asymmetries, piezoelectric effects, aging,
etc. can be compensated. The equations 1 to 6 show that
this is possible for any resistance values, since no
assumptions have been made about specific resistance values
in the sensor elements.
Further, Fig. 4a-d are to illustrate that only one vertical
Hall sensor element pair each is active during one
measurement phase, while the other is switched as voltage
divider. With reference to Fig. 2, this means that during
the individual measurement phases, only one side of the
sensor element arrangement 106 reacts to the magnetic field
lines 200, while the other one functions as voltage divider
independent of the currently applied magnetic field.
Thus, in the embodiment according to Fig. 3, preferably,
vertical 3-pin-Hall sensor element pairs are used for
implementing the second sensor element arrangement 104 and
the third sensor element arrangement 106. The measurement
phases described based on Fig. 4a-d can be performed
independent of the spatial direction of a Hall sensor
element. For using the spinning current method when using
vertical 3-pin sensors, i.e. for operating vertical 3-pin

sensors with a compensation method, two primitive elements
have to be used during operation.
According to one embodiment of the present invention, which
is illustrated in Fig. 3, two vertical 3-pin-Hall sensor
element pairs can be connected in parallel. The same are
always connected such that two of the same provide the HalL
voltage as a sensor, while the other two function as
voltage dividers and reduce the offset. For example, a
control voltage is applied between the contact terminals TO
and T2 in the measurement phase 0, with reference to Fig.
4al, this causes the formation of the Hall voltage UH
between the contact terminals Tl and T3 in the vertical
Hall sensor element pair 104ab. The vertical Hall sensor
element pair 104cd whose contacts are shifted by one phase,
operates merely as voltage divider, and makes no
contribution to the Hall voltage. The signal of the
vertical Hall sensor element pair 104cd is only used for
reducing the offset.
During the measurement phase 1, the control voltage as
applied between the contact terminal Tl and T3. This has
the effect that the Hall voltage is now formed at the
vertical Hall sensor element pair 104cd and the vertical
Hall sensor element pair 104ab only function as voltage
divider. The measurement phase 2 is the equivalent of
measurement phase 0, wherein the control voltage is then
applied between the contact terminals T2 and TO. The
vertical Hall sensor element pair 104ab then generates the
Hall voltage, whereas the sensor 2 functions again as
voltage divider. Analogously, the measurement phase 3 is
the equivalent of the measurement phase 1, the control
voltage is applied between the contact terminals T3 and Tl.
Then, the vertical Hall sensor element pair 104ab functions
as voltage divider and the vertical Hall sensor element
pair 104cd generates the Hall voltage.

Preferably, 3-pin-Hall sensors are used for sensors within
the invention. Basically, any other vertical Hall sensors,
e.g. 4-pin, 5-pin, 6-pin, etc. individual sensor elements
implemented as vertical Hall sensors can be used within the
invention. It is only critical that the same can be
operated with different sensitivities in operating phases,
or that the different sensitivities can be generated by
respective modes of operation. Here, both symmetrically
arranged individual sensor elements and symmetrically
arranged wirings of individual sensor elements, as has been
explained exemplarily with regard to the embodiments oE
Fig. 4, are possible. For example, in one embodiment of the
present invention, 5-pin sensors could be used, wherein one
5-pin individual element each realizes an inventive sensor
element arrangement, since 5-pin individual sensor elements
can already be operated both in the spinning current mode
and with different sensitivities. In this embodiment, the
symmetrically arranged 5-pin individual sensor elements are
operated simultaneously with different sensitivity, so that
the oppositely orientated calibration field components do
not fully compensate each other and a calibration field
component and/or a measurement field component can be
extracted. According to the invention, two symmetrically
arranged sensor elements are also suitable for detecting
both a measurement field component and a calibration field
component in different operating phases that can then be
extracted from the individual operating phases by
respective combinations of the measurement amounts. Thus,
such a sensor can also be calibrated during operation.
For simplifying the description of the inventive concept
for detecting spatial components of a magnetic field at a
reference point, as well as the calibration and measurement
method, the present description refers to a realization of
a magnetic field sensor based on vertical 3-pin sensor
elements for detecting the y- and x- components of the
calibration or measurement field, respectively, and to
horizontal sensor elements for detecting the respective z-

components. Basically, the inventive magnetic field sensor
and the inventive method are also possible by other
combinations of different individual sensor elements.
Fig. 5 shows a further embodiment of a magnetic field
sensor 100 according to an alternative embodiment of the
present invention. In Fig. 5, the first sensor element
arrangement 102, the second sensor element arrangement 104
and the third sensor element arrangement 106 are indicated
as dotted lines. Further, Fig. 5 shows the excitation line
108. As has already been discussed with respect to the
previous embodiment, individual elements are connected for
realizing the three sensor element arrangements 102, 104
and 106. Thus, the second sensor element arrangement 104
and the third sensor element arrangement 106 are realized,
for example, by the 3-pin vertical Hall sensor elements and
Hall sensor element pairs discussed with regard to Figs.
4a-d. In Fig. 5, the second sensor element arrangement 104
is realized by the four vertical Hall sensor elements 104a-
d, the third sensor element arrangement 106 by the vertical
Hall sensor elements 106a-d.
The first sensor element arrangement 102, which has so far
been illustrated as realized by a horizontal Hall sensor,
has four individual elements 102a-d in the embodiment
according to Fig. 5. Thus, the magnetic field sensor 100
illustrated m Fig. 5 is a combination of four horizontal
Hall sensors 102a-d and eight preferably vertical 3-pin
Hall sensors 104a-d and 106a-d. In a preferred embodiment,
the measurement levels measured by the respective sensors
are orthogonal to each other, wherein generally the
assumption suffices that the measurement levels of the
individual sensors run along linearly independent position
vectors, so that all spatial magnetic field components can
be detected.
In one embodiment in Fig. 4, four vertical 3-pin-Hall
sensor elements 104a-d and 106a-d are used for every axis

running tangentially to the surface of Fig. 5, wherein all
sensors are arranged symmetrically around a center or
reference point 101. It is assumed that the vertical Hall
sensor elements are connected corresponding to the above
description and that the sensors are operated in a spinning
current operation according to the above described
measurement phases 0 to 3. For explaining the inventive
calibratable magnetic field sensors and the calibration
method in more detail, the excitation line 108 is also
provided with current during the measurement phases.
Fig. 6 again shows the embodiment of a magnetic field
sensor 100 of Fig. 5, wherein, for clarity reasons, only
the reference numbers relevant for discussing the mode of
operation are indicated. In Fig. 6 current flows through
the excitation line 108, and thus a calibration field is
generated. In Fig. 6, an arrow indicating the direction of
the field lines of the calibration field -is next to every
vertical Hall sensor element. Further, it is assumed that
two of the vertical 3-pin-Hall sensors within one Hall
sensor element pair, such as the Hall sensor element pair
106c-d in Fig. 6, are operated in a spinning current mode.
Fig. 7 illustrates again the pattern of the magnetic field
lines 200 with regard to the sensor elements 106b, 106d,
102c, and 102d. Excitation with one excitation line does
not seem possible at first, since the generated field acts
on the vertical Hall sensor elements 106b and 106d in a
positive direction at one time, and in a negative direction
at another time. Considering the mode of operation of the
vertical 3-pin Hall sensor element 106a-d and 104a-d in the
spinning current operation, i.e. during the measurement
phases 0 to 3, it becomes clear that during one measurement
phase, one Hall sensor element pair each functions as
voltage divider, and thus detects no magnetic field
component.

Since the two vertical Hall sensor element pairs operated
in spinning current operation are only active alternately
within one sensor element arrangement, it is possible to
use a single excitation line 108. The current in the
excitation line is switched between the individual
measurement phases such that its excitation direction
changes and thus excites the Hall sensor element pairs in
the same direction in the respectively active state. For
the horizontal sensors 102c and 102d, this means that they
are excited in a positive direction in one measurement
phase and in a negative direction in the other measurement
phase. Thus, it is required to consider all four phases of
the spinning current operation such that the complete
sensor becomes operable.
The following table illustrates the control of the
inventive arrangement, wherein in the column control
voltage the terminals of the control current impression are
indicated, in the column Hall tapping the terminals where
the Hall voltage is tapped, in the column excitation the
polarity of the excitation current, in the column Hall
voltage the sign of the Hall voltage, and in the last two
columns the polarities of the calibration field components
of the calibration field:

The excitation line 108 is fed with a positive current in
the measurement phase 0, with a negative current in the
measurement phases 1 and 2 and again with a positive

current in the measurement phase 3. This has the effect
that a Hall voltage can be measured during a running
calibration. For the vertical Hall sensor elements 104a-d
and 106a-d, a change of sign of the excitation line 108
takes place between the measurement phases 0 and 1, such
that the calibration field is applied at the respectively
active vertical Hall sensor elements in the same direction.
Further, with regard to the vertical Hall sensor elements
104a-d and 106a-d, a change of sign of the calibration
field takes place from the measurement phases 0 to 1 to the
measurement phases 2 and 3, which results in the
calibration field components canceling each other out when
adding all four spinning current phases. Since in the case
of adding the four measured Hall voltages UH during the
four measurement phases, the actual Hall voltages are added
in a sign-correct manner, in this process only the portion
that can be attributed to the measurement field remains.
With regard to the horizontal Hall sensor elements 102a-d,
the calibration field is applied to all horizontal Hall
sensor elements in the same direction. This means that with
every change of sign of the current in the excitation line
1208, a change of sign of the respective calibration field
components and the attributed measured voltage takes place.
This again has the effect that during adding all
measurement signals measured in the four spinning current
phases, the portions of the calibration field just cancel
each other out, whereas the portions of the measurement
field overlay in a constructive manner and are thus, in the
ideal case, adjusted for the calibration field. In
practice, a reduction of the calibration field components
to tolerance ranges in the order of less than 10%, 1%, or
0.1% of the total measurement value is possible.
In order to be able to perform calibration during a running
measurement, i.e. when the magnetic field sensor is in a
magnetic field, the same process is applied. With regard to
the vertical Hall sensor elements 104a-d and 106a-d, the

calibration field is applied in a positive direction in the
measurement phases 0 and 1, whereas the calibration field
is applied in a negative direction to the active vertical
Hall sensor elements in the measurement phases 2 and 3. The
calibration Hall voltage can now be obtained by adding the
measurement signals from the first two phases and
subtracting the measurement signals of the last two
measurement phases. This results in the actual signals to
be measured, which means measurement signals attributed to
the measurement field, ]ust canceling each other out,
whereas only those measurement signals attributable to the
calibration field overlap in a constructive manner. With a
respective combination of the measurement signals from the
individual measurement phases, a calibration field
component can be extracted, even when at the same time a
further magnetic field to be measured is present.
With regard to the horizontal Hall sensor elements 102a-d,
the calibration field is applied in a positive direction in
the measurement phases 0 and 3, and in a negative direction
in the measurement phases 1 and 2. The calibration Hall
voltage attributable to the calibration field can now be
obtained by adding the measurement signals of the
measurement phases 0 and 3 and subtracting the measurement
signals of the measurement phases 1 and' 2. In this case, by
respectively combining, a measurement signal, which is
merely attributable to the calibration field, can be
extracted since in the ideal case, the measurement field
components cancel each other out completely. In practice, a
reduction of the measurement field components to tolerance
ranges in the order of less than 10%, 1%, or 0.1% of the
total measurement value is possible.
The measurement signal attributable to the measurement
field component results in all these Hall sensors by adding
measurement signals measured in the four spinning current
measurement phases.

Maximum Hall voltage = sum of the signals of the individual
measurement phases 0 to 3.
For extracting the calibration field component, the
measurement signals from the four measurement phases or
spinning current phases, respectively, are added as
follows:
Calibration field component of the vertical sensors =
measurement phase 0 + measurement phase 1 - measurement
phase 2 - measurement phase 3.
Calibration field component of the horizontal sensors =
measurement phase 0- measurement phase 1 - measurement
phase 2 + measurement phase 3.
In principle, it is possible to provide other combination
options by reversing the polarity of the excitation current
and exchanging the measurement phases. According to the
invention, it is generally possible to extract the
measurement field component with reduced calibration field
component, or the calibration field component with reduced
measurement field component, respectively, by different
combinations of the measurement signals. It can be seen
that the measurement signal component attributable to the
measurement field is theoretically eliminated by this
linear combination, and only one calibration field
component remains. In a practical application, the
influence of a measurement field can be significantly
reduced by a linear combination of the described type for
extracting a calibration field component. By another linear
combination, it is possible to mostly suppress the
calibration field component for extracting an offset-
compensated measurement field component. In practice, a
suppression to portions in the order of less than 10%, 1%,
or 0.1% of the total measurement value is possible.

Fig. 8 shows a further embodiment of the first sensor
element arrangement 102. Fig. 8 shows an alternative
embodiment wherein two horizontal Hall sensor element pairs
each are placed in a square, wherein the individual
horizontal Hall sensor element pairs are arranged
diagonally to the reference point 101. Here, the first
sensor element arrangement 102 consists overall of four
horizontal Hall sensor elements 102a-d. Further, every Hall
sensor element 102a-d has four contact electrodes K1-K4. In
the embodiment shown in Fig. 8, the contact electrodes Kl,
the contact electrodes K2, the contact electrodes K3, and
the contact electrodes K4 of the individual Hall sensor
elements 102a-d are connected in parallel and hardwired to
each other without interposed switches. In the present
illustration, the contact electrodes Kl and the contact
electrodes K3 of the Hall sensor elements 102a-d form the
current impression contacts, whereas the contact electrodes
K2 and the contact electrodes K4 of the Hall sensor
elements 102a-d provide the measurement terminals for
detecting a Hall voltage. The contact electrodes for
supplying an operating current and the contact electrodes
for detecting a Hall voltage are arranged in the individual
Hall sensor elements, such that the current direction of
the impressed operating current is respectively
perpendicular to the direction of the tapped Hall voltage.
In the present arrangement, the operating current
directions in the two Hall sensor elements of every Hall
sensor element pair, which means 102a and 102d or 102b and
102c, respectively, are each rotated by 90° to each other.
The current directions of the second Hall sensor element
pair are offset at an angle of 45° with regard to the
current directions of the first Hall sensor element pair.
In the practical implementation of the inventive Halls
sensor arrangement, the angle by which the operating
current directions in the two Hall sensor elements of every
pair are rotated to each other can deviate from the ideal

value of 90°, and can be, for example, in a range of, e.g.,
between 80° and 100°, wherein the angles in this range can
be considered as angles of substantially 90°in terms of the
present embodiment. The hardwired contact electrodes Kl,
K2, K3, and K4 of the Hall sensor elements 102a-d are
connected to switches SI, S2, S3 and S4 that can each be
switched between four positions, i.e. between the contact
electrodes Kl, K2, K3, and K4. With the switches SI to S4,
the contact electrodes Kl to K4 can be switched together as
supply terminals for supplying an operating current IB, or
as measurement terminals for detecting a Hall voltage UH in
the individual measurement phases of the Hall sensor
arrangement. Thus, switching the switches makes a spinning
current method within the first sensor element arrangement
102 possible.
In principle, further embodiments are possible as well. A
further embodiment of a Hall sensor arrangement that is not
explicitly illustrated here can, for example, be that more
than two pairs of Hall sensor elements are used. This
applies as well with regard to the vertical Hall sensor
element arrangements that are generally also not limited to
the usage of two or four Hall sensor elements. Even in the
case that more Hall sensors are used, the current
directions in the two Hall sensor elements of every pair
can each be substantially offset to each other by 90° as it
is also the case in the embodiment of Fig. 8. Here, the two
Hall sensor elements of one pair also have to be
geometrically equal and closely adjacent with regard to the
dimension of the Hall sensor elements and can be arranged
below, next to, or diagonally to each other in the overall
sensor arrangement. With regard to the geometry of the
arrangement, a measure of symmetry around the reference
point to be measured is required within certain tolerance
ranges. The current directions of the at least two Hall
sensor element pairs are each rotated to each other and by
an angle of 90°/n, wherein n is the number of all used Hall
sensor element pairs, wherein n > 2. If, for example, three

Hall sensor elements are used, the current directions in
the individual Hall sensor element pairs will be offset by
an angle of substantially 30°. The sensor element pairs of
the sensor arrangement are arranged either next to each
other, or in the secondary diagonal, wherein the Hall
sensor elements are in pairs as close as possible to each
other.
In summary, it can be stated with regard to the inventive
concept of the magnetic 3D point sensor calibratable during
measurement operation that magnetic sensors according to
the embodiments of the present invention also require only
a single excitation conductor. They offer the advantage
that all three field components can be measured in very
good approximation at one point, wherein offsets are
caused, for example, by device tolerances, contaminations
in the semiconductor material, structure inhomogeneties in
the semiconductor material, etc., can be compensated, for
example, by the spinning current principle, and that the
measurement values can then be provided with little offset.
By using the excitation loop that can have an arbitrary
number of windings, a simple wafer-test, which means an on-
chip-test of all three sensors becomes possible. Further,
by combining the measurement signals from the individual
measurement phases, it is possible to allow a self-test
during the running measurement operation, since both
measurement signal portions attributable to the measurement
field components and measurement signal portions
attributable to calibration field components can be
significantly reduced. Thus, it is possible to perform
sensitivity calibration at such a magnetic field sensor
during operation. The excitation loop itself can also be
tested, since a failure of all three sensors with separate
evaluation electronic is very unlikely.
Further, it should be noted that the present invention has
been explained using the example of vertical 3-pm-Hall
sensors, but the same is generally not limited to these.

For example, 5-pin-Hall sensors (see, e.g., DE 101 50 955 and DE 101 50
950) or generally any sensors can be used, wherein circular or circular-
segment shaped arrangements are also possible. With regard to the
geometry of the magnetic field sensor, the used sensor element
arrangements should each detect the magnetic field at a common
reference point, which can substantially be obtained by symmetrical
arrangements in pairs around the reference point analogously to the
above specification. The measurement method, which means the
compensation method and the calibration method is then to be adapted to
the respective Hall sensors and their geometry.
It should particularly be noted that depending on the circumstances, the
inventive scheme can also be implemented in software. The
implementation can be performed on digital memory media, particularly a
disc, or a CD with electronically-readable control signals that can
cooperate with a programmable computer system and/or micro-controller
such that the respective method is performed. Generally, the invention
also consists of a computer program product with a program code for
performing the inventive method stored on a machine-readable carrier
when the computer program product runs on a computer and/or micro-
controller. In other words, the invention can also be realized as a
computer program with a program code for performing the method, when
the computer program runs on a computer and/or micro-controller.
For reasons of clarity, the control or evaluation logic, respectively, is not
illustrated in Fig. 9. The four contact electrodes 906a-d are subdivided
into two opposing control current contact electrodes 906a and 906c,
which are provided for generating a current flow IH through the active
region 902, and further into two opposing voltage tapping contact

electrodes 906b and 906d, which are provided for tapping a Hall voltage
UH, which occurs with an applied magnetic field! perpendicular to the
current flow in the active region 910 and the applied magnetic field, as a
sensor signal. By impressing the current flow IH between different contact
electrodes and correspondingly tapping the Hall voltage UH at the other
contact electrodes perpendicular to the current flow, compensation
methods can be implemented, which allow the compensation of tolerances
occurring in the Hall sensors, for example, due to production tolerances,
etc, across several measurement cycles.
As can be seen from the horizontal Hall sensor element 900 illustrated in
Fig. 9a, the active region is defined between the contact terminals 906a-
d, such that the active region has an effective length L and an effective
width W. The horizontal Hall sensor 900 illustrated in Fig. 9a can be
produced relatively easily with conventional CMOS-processes (CMOS =
Complementary Metal Oxide Semiconductor) for producing semiconductor
structures.
Further, apart from the horizontal Hall senor elements, implementations
of the so-called vertical Hall sensor element 920 is basically illustrated in
Fig. 9b, wherein vertical means a level perpendicular to the level of the
chip surface (X-Y-Level). In the vertical Hall sensor element 920
illustrated in Fig. 9b, the preferably n-doped active semiconductor region
922 has a depth T. As illustrated in Fig. 9b, the vertical Hall sensor
element has three contact regions 926a-c, which are bordering on the
main surface of the semiconductor substrate 924, wherein the contact
terminals 926a-c are all within the active semiconductor region 922. Due
to the three contact regions, this variation of vertical Hall sensor elements
is also called 3-pin sensor.

Thus, the vertical Hall sensor element 920 illustrated in Fig. 9b has three
contact regions 926a-c along the main surface of the active
semiconductor region 922, wherein the contact region 926a is connected
to contact terminal A, the contact region 926b is connected to contact
terminal B, and wherein the contact region 926c is connected to a contact
terminal C. If a voltage is applied between the two contact terminals A
and C, a current flow IH through the active semiconductor region 922
results, and a Hall voltage UH, which is perpendicular to the current flow
IH and the magnetic fieldl, can be measured at the contact terminal B.
The effective regions of the active semiconductor regions 922 are
predetermined by the depth T of the active semiconductor region 922 and
the length L according to the distance between the current feeding
contact electrodes 926a and 926c.
Horizontal and vertical Hall sensors, as well as the methods for reducing
offsets resulting from device tolerances, such as contaminations,
asymmetries, piezoelectric effects, aging effects, etc, for example the
spinning current method, are already known in literature, e.g. R. S.
Popovic, "Hall Effect Devices, Magnetic Sensors and Characterization of
Semiconductors", Adam Hilger, 1991, ISBN 0-7503-0096-5. Vertical
sensors operated by spinning-current frequently consist of two or four
individual sensors, as it is for example described in DE 101 50 955 and DE
101 50 950.
Further, apart from the variation of the 3-pin vertical Hall sensor
elements, which are also described in DE 101 50 955 and De 101 50 950.
In the 5-pin Hall sensor elements there is also the possibility of
performing a measurement compensated by tolerances of the individual
devices with a compensation method extending across several
measurement phases, for example, a spinning current method could be

used here as well.
The spinning current techique consists of continuously cyclically rotating
the measurement direction for detecting the Hall voltage at the Hall
sensor element with a certain clock frequency, for example by 90°, and to
sum it across all measurement signals of a full rotation by 360°. Thus, in
a Hall sensor element having four contact regions, two of which are
arranged in pairs, each of the contact pairs is used both as control current
contact regions for current feeding and as measurement contact regions
for tapping the Hall signal depending on the spinning current phase. Thus,
in a spinning current phase or in a spinning current cycle, respectively,
the operating current (control current IH) flows between two associated
contact regions, wherein the Hall voltage is tapped at the two other
contact regions associated to each other.
In the next cycle, the measurement direction is rotated further by 90°, so
that the contact regions used for tapping the Hall voltage in the previous
cycle are now used for feeding the control current. By summation across
all four cycles or phases, respectively, offset voltages caused by
production or material approximately cancel each other out, such that
only the actually magnetic field dependent portions of the signals remain.
This process can also be applied to a larger number of contact pairs,
wherein, for example, with four contact pairs (having eight contact
regions) the spinning current phases are cyclically rotated by 45°, in order
to sum up all measurement signals across a full rotation by 360°.
In horizontal Hall sensors, four sensors are also frequently used, wherein,
with an appropriate arrangement, the offset can additionally be heavily
reduced by spatial spinning current operation, see e.g. DE 199 43 128.
If a magnetic field is to be measured for several spatial directions, mostly

separate Hall sensor elements are used. The usage of separate sensors,
for example for detecting the three spatial directions of a magnetic field,
generally causes the problem that the magnetic field to be measured is
not measured at one point, but at three different points. Fig. 10 illustrates
this aspect, wherein Fig. 10 shows three Hall sensors 1002, 1004, and
1006. The first Hall sensor 1002 is provided for detecting a y-spatial
component, the second Hall sensor 1004 for detecting a z-spatial
component, and the third Hall sensor 1006 for detecting an x-spatial
component. The individual sensors 1002, 1004, and 1006 measure the
corresponding spatial components of a magnetic field approximately at
the respective centers of the individual sensors.
An individual sensor can again consist of several Hall sensor elements.
Fig. 10 shows exemplarily three individual sensors having four Hall sensor
elements each, wherein in Fig. 10 exemplarily a horizontal Hall sensor
1004 is assumed, which detects a z-component of the magnetic field to be
measured, and a vertical Hall sensor 1002 and 1006 each for the y- or x-
component of the magnetic field to be measured. The arrangement for
detecting the spatial magnetic field components, exemplarily illustrated in
Fig. 10, has the problem that the magnetic field cannot be measured at
one point, but at the respective centers of the individual sensors. This
inevitably causes a corruption, since no exact evaluation of the magnetic
field is possible based on the magnetic field components of the magnetic
field sensors detected at different positions.
A further aspect of the detection and evaluation of the magnetic fields by
Hall sensor elements is the calibration of the individual elements.
According to the prior art, Hall sensor elements are mostly provided with
so-called excitation lines, which allow the generation of a defined
magnetic field at the measurement point of an individual sensor, for

subsequently obtaining calibration of the sensor by comparing or
associating the measured Hall voltage to the defined magnetic field.
Excitation conductors allow the generation of an artificial magnetic field at
a Hall sensor, which allows a simple wafer test, i.e. a test directly on the
substrate as well as a self-test and a sensitivity calibration during
operation, see Janez Trontelj, "Optimization of Integrated Magnetic
Sensor by Mixed Signal Processing, Proceedings of the 16th IEEE Vol. 1.
This is particularly interesting in security critical areas, e.g. in the
automobile industry or also in medical technology, since self-monitoring of
the sensors is possible during operation.
If, for example, several individual sensors are used for detecting the
spatial components of a magnetic field, as exemplarily shown in Fig. 10,
every individual sensor requires a respective excitation line for calibration,
and the individual sensors are further calibrated individually. It follows
that the calibration effort scales with the number of individual sensor
elements, and, in the case of spatially detecting three magnetic field
components, the same is increased three times compared to the
calibration effort of an individual sensor.
One approach for allowing an evaluation of a magnetic field, i.e. a
measurement at one point, is a 3D sensor of the Ecole Polytechnique
Federal Lausanne EPFL, cf. C. Schott, R. S. Popovic, "Integrated 3D Hall
Magnetic Field Sensor", Transducers '99, June 7-10, Sensai, Japan, VOL.
1, PP. 168-171, 1999. Fig. 11 schematically shows such a Hall sensor
1100, which is implemented on a semiconductor substrate 1102. First, the
3D sensor has four contact areas 1104a-d, across which currents can be
impressed in the semiconductor substrate 1102. Further, the 3D sensor
has four measurement contact areas 106a-d, via which the different

magnetic components can be detected. A wiring 1110 is illustrated on the
right-hand side of Fig. 11. The shown wiring composed of four operational
amplifiers 1112a-d evaluates the Hall voltages proportional to the
individual magnetic field components and outputs the respective
components at the terminals 1114a-c in the form of signals Vx, Vy, and
Vz.
The illustrated sensor has the problem that the same can only be
calibrated by a defined externally generated magnetic field and has no
individual excitation line. Further, due to its structure and its mode of
operation, this sensor cannot be operated with the compensation method,
e.g. spinning current method. Further, another problem of the structure
shown in Fig. 11 is that such a semiconductor device has offset voltages
due to contamination of the semiconductor material, asymmetries in
contacting, variances in the crystal structure, etc., which cannot be
suppressed by a respective spinning-current suitable compensation wiring.
Thus, the sensor does measure magnetic field components at the focused
point, but has a high offset and is thus only suitable for precise
measurements in a limited manner. Fig. 12 shows a 3D sensor suitable for
compensation (spinning-current), which detects spatial magnetic field
components at a measurement point, and which is discussed by Enrico
Schurig in "Highly Sensitive Vertical Hall Sensors in CMOS Technology",
Hartung-Gorre Verlag Konstanz, 2005, Reprinted from EPFL Thesis N°
3134 (2004), ISSN 1438-0609, ISBN 3-86628-023-8 WW 185 ff. The top
part of Fig. 12 shows the 3D sensor of Fig. 10 consisting of three
individual sensors. The upper part of Fig. 12 shows the three separate
individual sensors 1002, 1004, and 1006 for detecting the spatial
magnetic field components. The bottom part of Fig. 12 shows an
alternative arrangement of the individual sensors.

In this arrangement, the sensor 1004 remains unaltered, since the
measurement point of the sensor 1004 is in the center of the arrangement
1200 in Fig. 12, further, the two individual sensors 1002 and 1006 consist
of individual elements that can be separated. The sensor 1002 is now
subdivided into two sensor parts 1202a and 1202b and arranged
symmetrically around the center of the sensor element 1004. An analog
method is performed with the sensor 1006, such that the same is also
divided into two sensor parts 1206a and 1206b that are arranged
symmetrically around the center of the sensor elements 1004, along the
respective spatial axis. Due to the symmetrical arrangement of the
individual sensor elements, the magnetic field is detected at one point,
which lies in the geometrical center of the arrangement. One
disadvantage of this arrangement is that the sensor can only be calibrated
across several excitation lines. In the following, the arrangement 1200 in
the bottom part of Fig. 12 will be referred to as pixel cell without
calibration.
Dragana R. Popvic et al. describes in "Three-Axis Teslameter with
Integrated Hall Probe Free from the Planar Hall Effect" a three-
dimensional Hall Sensor integrated in a semiconductor chip. Further, a
wiring of the magnetic field sensor is described, which allows to
compensate measurement tolerances caused, for example, by
temperature drift.

WE CLAIM:
1. A magnetic field sensor (100) calibratable during measurement
operation for detecting first, second, and third spatial components
BZ, By and Bx of a magnetic field at a reference point (101), wherein
the magnetic field has first, second, and third measurement field
components BMz, BMy and BMx, and/or first, second, and third
calibration field components BKz, BKy and BKx, comprising:
a first sensor element arrangement (102) for detecting the first
magnetic field component Bz having a first measurement field
component BMz and/or a first calibration field component BKz, with
respect to a first spatial axis z at the reference point (101);
a second sensor element arrangement (104) for detecting the
second magnetic field component By having a second measurement
field component BMy and/or a second calibration field component
BKy, with respect to a second spatial axis y at the reference point
(101);
a third sensor element arrangement (106) for detecting the third
magnetic field component Bx having a third measurement field
component BMx and/or a third calibration field component BKx, with
respect to a third spatial axis x at the reference point (101); and
an excitation line (108) arranged such with respect to the first
(102), second (104), and third sensor element arrangements (106)
that when impressing a predetermined current into the excitation
line (108), a first predetermined calibration field component BKz with
respect to the first spatial axis z in the first sensor element
arrangement (102) is generated, a second predetermined calibration
field component BKy with respect to the second spatial axis y in the
second sensor element arrangement (104) is generated, and a third
predetermined calibration field component BKx with respect to the

third spatial axis x in the third sensor element arrangement (106) is
generated, wherein the three spatial axes z, y, and x run along
linearly independent position vectors.
2. The magnetic field sensor as claimed in claim 1, wherein the first
(102), second (104) and third sensor element arrangements (106)
can be operated in a plurality of operating phases, wherein each of
the first (102), second (104), and third sensor element
arrangements (106) is implemented to provide, in every operating
phase, a measurement signal attributable to the operating phase.
3. The magnetic field sensor as claimed in claim 2, wherein each of
the first (102), second (104) and third sensor element
arrangements (106) is implemented to provide the measurement
signals attributed to the operating phases, wherein the
measurement signals attributed to the operating phases can be
combined to a first total measurement value by a first linear
combination, such that the influenc of the measurement field
component in the first total measurement value is reduced, or the
measurement signals attributed to the operating phases can be
combined to a second total measurement value by a second linear
combination, such that the influence of the calibration field
component in the second total measurement value is reduced.
4. The magnetic field sensor as claimed in claims 1 to 3, wherein the
first sensor elment arrangement (102) has a Hall sensor element
horizontal with respect to a main surface of the magnetic field
sensor.
5. The magnetic field sensor as claimed in one of claims 1 to 4,
wherein the first sensor element arrangement (102) has a plurality

of Hall sensor elements horizontal with respect to a main surface of
the magnetic field sensor, wherein the geometrical arrangement of
the plurality of horizontal Hall sensor elements is symmetrical in
pairs with respect to the reference point (101) and the Hall sensor
elements are coupled to each other such that the magnetic field
component can be detected in an offset-compensated manner.
6. The magnetic field sensor as claimed in one of claims 1 to 5,
wherein the second sensor element arrangement (104) has at least
two Hall sensor elements vertical with respect to a main surface of
the magnetic field sensor, wherein the geometrical arrangement of
the at least two vertical Hall sensor elements is symmetrical in pairs
with respect to the reference point (101), and that are coupled to
each other such that the magnetic field component can be detected
in an offset-compensated manner.
7. The magnetic field sensor as claimed in one of claims 1 to 6,
wherein the third sensor element arrangement (106) has at least
two Hall sensor elements vertical with respect to a main surface of
the magnetic field sensor, wherein the geometrical arrangement of
the at least two vertical Hall sensor elements is symmetrical in pairs
with respect to the reference point (101), and that are coupled to
each other such that the magnetic field component can be detected
in an offset-compensated manner.
8. A method for calibrating a magnetic field sensor during
measurement operation by detecting first, second, and third spatial
components Bz, By and Bx of a magnetic field at a reference point
(102), wherein the magnetic field has first, second, and third
measurement field components BMz, BMy, BMx and/or first, second,

and third calibration field components BKz, BKy and BKx, comprising:
detecting the first magnetic field component B2 having a first
measurement field component BMz and/or a first calibration field
component BKz with respect to the first spatial axis z at the
reference point;
detecting the second magnetic field component By having a second
measurement field component BMy and/or a second calibration field
component BKy with respect to the second spatial axis y at the
reference point;
detecting the third magnetic field component Bx having a third
measurement field component BMy and/or a third calibration field
component BKx with respect to the third spatial axis x at the
reference point; and
generating the first, second, and third calibration field components
BKZ, BKy and BKx with respect to the first, second, and third spatial
axes z, y and x, wherein the first, second, and third spatial axes run
along linearly independent position vectors.
9. The method as claimed in claim 8, wherein the steps of detecting
are repeated during a plurality of operating phases, wherein
measurement signals attributed to the first magnetic field
component Bz, to the second magnetic field component By, and to
the third magnetic field component Bx in the operating phases are
detected.
10. The method as claimed in claims 8 or 9, wherein a step of first
linearly combining the measurement signals of a magnetic field
component attributed to the operating phases to a first total
measurement value, such that the influence of the measurement

field component in the first total measurement value is reduced, or a
step of second linearly combining the measurement signals of a
magnetic field component attributed to the operating phases to a
second total measurement value, such that the influence of the
measurement field component in the second total measurement
value is reduced.
11. The method as claimed in claim 10, wherein the step of second
combining the measurement signals of a magnetic field component
attributed to the operating phases to a second total measurement
value is performed such that the portion of the calibration field
component in the second total measurement value is reduced to less
than 10%, 1%, or 0.1% of the second total measurement value.
12. The method as claimed in one of claims 8 to 11, wherein a step of
combining the measurement signals of a magnetic field component
attributed to the operating phases, such that the magnetic field
component can be detected in an offset-compensated manner.
13. The method as claimed in one of claims 8 to 12, wherein the
operating phases are implemented according to a spinning current
method.
14. The method as claimed in one of claims 8 to 13, wherein:
storing excitation current strengths, measurement field components,
or calibration field components for calibration;
attributing the excitation current strengths to the calibration field
components or magnetic field strengths, respectively; and

providing value pairs of measurement field components and
magnetic field strengths.

ABSTRACT

TITLE: MAGNETIC 3D SENSOR CALIBRATABLE DURING
MEASUREMENT
A magnetic field sensor (100) calibratable during measurement operation
for detecting first, second, and third spatial components Bx, By and Bx of a
magnetic field at a reference point (101), wherein the magnetic field has
first, second, and third measurement field components BMz, BMy and BMX,
and first, second, and third calibration field components BKz, BKy, and BKx.
The magnetic field sensor (100) comprises a first sensor element
arrangement (102) for detecting the first magnetic field component Bz
having a first measurement field component BMz and a first calibration
field component BKz with respect to a first spatial axis z at the reference
point (101), a second sensor element arrangement (104) for detecting the
second magnetic field component By having a second measurement field
component BMy and a second calibration field component BKY with respect
to a second spatial axis y at the reference point (101) and a third sensor
element arrangement (106) for detecting the third magnetic field
component BMx and a third calibration field component BKx with respect to
a third spatial axis x at the reference point (101). Further, the magnetic
field sensor (100) comprises an excitation line (108) arranged such with
respect to the first (102), second (104), and third sensor element
arrangements (106) that when impressing a predetermined current into
the excitation line (108), a first predetermined calibration field component
BKz with respect to the first spatial axis x in the first sensor element
arrangement (102) is generated, a second predetermined calibration field
component BKy with respect to the second spatial axis y in the second
sensor element arrangement (104) is generated, and a third
predetermined calibration field component BKx with respect to the third
spatial axis x in the third element arrangement (106) is generated,
wherein the three spatial axes z, y, and x run along linearly independent
position vectors.