EP1613927A1

EP1613927A1 - Method and apparatus for an integrated gps receiver and electronic compassing sensor device

Info

Publication number: EP1613927A1
Application number: EP04775885A
Authority: EP
Inventors: William F. Witcraft; Tamara K. Bratland; Cheisan J. Yue; Hong Wan
Original assignee: Honeywell International Inc
Current assignee: Honeywell International Inc
Priority date: 2003-04-15
Filing date: 2004-04-13
Publication date: 2006-01-11
Also published as: TW200510754A; WO2005017456A1

Abstract

At least one magnetic field sensing device and GPS receiver integrated in a discrete, single-chip package, and a method of manufacture for the same. Rather than requiring at least two separate chips to be used to realize GPS positioning and compassing capabilities in a single device, an integrated, single chip solution can be used. A single chip integration of a GPS receiver and at least one magnetic filed sensing device can reduce the physical space required to provide positioning and electronic compassing capabilities in a single device, and therefore allow such devices to be smaller, lighter, and possibility more portable.

Description

METHOD AND APPARATUS FOR AN INTEGRATED GPS RECEIVER AND ELECTRONIC COMPASSING SENSOR DEVICE

RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application Nos. (1)

60/475,191, filed June 2, 2003, entitled "Semiconductor Device Integration with a

Magneto-Resistive Sensor," naming as inventors Lonny L. Berg and William F. Witcraft;

(2) 60/475,175, filed June 2, 2003, entitled "On-Die Set/Reset Driver for a Magneto-

Resistive Sensor," naming as inventors Mark D. Amundson and William F. Witcraft; and

(3) 60/462,872, filed April 15, 2003, entitled "Integrated GPS Receiver and Magneto-

Resistive Sensor Device," naming as inventors William F. Witcraft, Hong Wan, Cheisan J. Yue, and Ta ara K. Bratland. The present application also incorporates each of these

Provisional Applications in their entirety by reference herein.

This application is also related to and incorporates by reference U.S.

Nonprovisional Application Nos. (1) , Honeywell Docket No. H0004948US, filed concurrently, entitled "Semiconductor Device and Magneto-Resistive Sensor

Integration," naming as inventors Lonny L. Berg, William F. Witcraft, and Mark D.

Amundson; and (2) , Honeywell Docket No. H0004956US, filed concurrently,

entitled "Integrated Set/Reset Driver and Magneto-Resistive Sensor," naming as inventors

Lonny L. Berg and William F. Witcraft.

BACKGROUND

1. Field of the Invention The present invention relates in general to magnetic field and current sensing, and

more particularly to integrating a GPS receiver with a compassing sensor.

2. Description of Related Art Magnetic field sensors have applications in magnetic compassing, ferrous metal

detection, and current sensing. They may be used to detect variations in the magnetic

field of machine components and in the earth's magnetic field, as well as to detect underground minerals, electrical devices, and power lines. For such applications, an

anisotropic magneto-resistive (AMR) sensor, a giant magneto-resistive (GMR) sensor, a colossal magneto-resistive (CMR) sensor, a hall effect sensor, a fluxgate sensor, or a coil

sensor that is able to detect small shifts in magnetic fields may be used.

Magneto-resistive sensors, for example, may be formed using typical integrated circuit fabrication techniques. Permalloy, a ferromagnetic alloy containing nickel and

iron, is typically used as the magneto-resistive material. Often, the permalloy is arranged

in thin strips of permalloy film. When a current is run through an individual strip, the

magnetization direction of the strip may form an angle with the direction of current flow.

As the magnetization direction of the strip changes relative to the current flow, its

effective resistance also changes. Strip resistance reaches a maximum when the

magnetization direction is parallel to the current flow, and reaches minimum when the

magnetization direction is perpendicular to the current flow. Such changes in strip

resistance result in a change in voltage drop across the strip when an electric current is run through it. This change in voltage drop can be measured and used as an indication of

change in the magnetization direction of external magnetic fields acting on the strip.

To form the magnetic field sensing structure of a magneto-resistive sensor, several

permalloy strips may be electrically connected together. The permalloy strips may be

placed on the substrate of the magneto-resistive sensor as a continuous resistor in a

"herringbone" pattern or as a linear strip of magneto-resistive material, with conductors

across the strip at an angle of 45 degrees to the long axis of the strip. This latter

configuration is known as "barber-pole biasing." The positioning of conductors in a

"barber-pole biasing" configuration may force the current in a strip to flow at a 45 -degree angle to the long axis of the strip. These magneto-resistive sensing structure designs are

discussed in US Patent No. 4,847,584, July 11, 1989, to Bharat B. Pant, and assigned to

the same assignee as the current application. US Patent No. 4,847,584 is hereby fully

incoφorated by reference. Additional patents and patent applications describing magnetic sensor technologies are set forth below, in conjunction with the discussion of FIG. 4. Magnetic sensors often include a number of straps through which current may be run for controlling and adjusting sensing characteristics. For example, magnetic sensor

designs often include set, reset, and offset straps. These straps can improve the

performance and accuracy of magnetic sensors, but require driver circuitry for proper

operation. Such circuitry has typically been located off-chip from the magnetic sensor,

resulting in space inefficiencies. Similarly, other components, such as operational

amplifiers, transistors, capacitors, etc., have typically been implemented on a separate

chip from the magnetic sensor. Both signal conditioning and electrostatic discharge

circuitry, for example, are typically located off-chip. Although such off-chip circuitry is

adequate for many applications, for those where physical space is at a premium it would be desirable to have necessary circuitry integrated into a single-chip magnetic sensor,

thereby conserving space. One consequence of the space inefficiencies of multiple-chip magnetic sensors is

the stunting of technological advances in the integration of compassing and positioning

technologies. To take advantage of the functionality of both magnetic sensors and

positioning technologies, at least one additional positioning chip is required. The Global

Positioning System (GPS), the leading positioning technology, enables a GPS receiver to

determine its position on the earth from a set of concurrently received signals transmitted

by at least three of a constellation of GPS satellites. GPS receivers can also determine heading using the same signals used to determine position. However, in order to obtain

an accurate heading, the GPS receiver must be moving at a speed of at least 10 mph. As a

result, GPS has been successfully used for positioning in both handheld and vehicle- mounted systems, as well as for navigation in vehicle mounted systems (when traveling at

a speed of at least 10 mph). By combining the functionality of a magnetic field sensing device with that of a

GPS receiver, a user can determine both direction (from the magnetic field sensing

device) and position (from the GPS receiver), both when stationary and when moving.

However, for handheld applications, such a combination may be unwieldy and inefficient

due to the physical space requirements of a GPS receiver chip, a magnetic field sensing

device chip, and a potential for additional chips required for magnetic field sensing device

circuitry. Thus, a single-chip design that would minimize the physical space required to

integrate a GPS receiver with a magnetic field sensing device would be desirable. SUMMARY One exemplary embodiment provides a single package sensor device. The single package sensor device is comprised of GPS receiver circuitry and a magnetic field sensing device adjacent to the GPS receiver circuitry. The single-package integration of the GPS receiver circuitry and the magnetic field sensing device can be accomplished in the following two ways: (1) a single-die, single package solution and (2) a multiple-die, single-package solution. Because such an integrated device may be manufactured as a single package, the user may realize advantages that include possible cost reduction, reduced size, and increased functionality, among others. These as well as other aspects and advantages of the present invention will become apparent to those of ordinary skill in the art by reading the following detailed description, with appropriate reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the present invention are described with reference to the

following drawings, wherein:

FIGs. 1A-1C are simplified block diagrams illustrating embodiments of the

present invention;

FIGs. 2A-2C are simplified block diagrams illustrating embodiments of the

present invention with included shielding features;

FIG. 3 is a simplified block diagram illustrating a GPS receiver and a magneto-

resistive sensor integrated on a single die in accordance with an embodiment of the

present invention;

FIG. 4 is a simplified block diagram illustrating a device-architecture for a GPS receiver and a magneto-resistive sensor integrated in a single die in accordance with an

embodiment of the present invention;

FIG. 5 is a simplified block diagram illustrating a magneto-resistive sensor with

GPS receiver components in accordance with an exemplary embodiment of the present

invention;

FIG. 6 is a simplified block diagram illustrating a typical GPS receiver;

FIG. 7 is a simplified block diagram illustrating an exemplary use for an integrated

GPS receiver and magneto-resistive sensor in accordance with an embodiment of the

present invention; and

FIG. 8 is a simplified block diagram illustrating an exemplary use for an integrated

present invention. DETAILED DESCRIPTION In view of the wide variety of embodiments to which the principles of the present

invention can be applied, it should be understood that the illustrated embodiments are

exemplary only, and should not be taken as limiting the scope of the present invention. FIGs. 1A-1C are block diagrams illustrating an integration of a GPS receiver with

a magnetic field sensing device (i.e. a magneto-resistive sensor). The device 100 of FIGs.

IA and IB includes a first portion 102, including a magneto-resistive sensor and wiring,

and a second portion 104, including GPS receiver circuitry. In a preferred embodiment, the second portion 104 also includes signal conditioning circuitry and circuitry for ESD

(electro-static discharge) protection for the magneto-resistive sensor in the first portion 102. As discussed below, the second portion 104 is particularly amenable to standard

semiconductor fabrication techniques, such as those used for CMOS (complementary

metal oxide semiconductor). The first and second portions 102, 104 are included within a single chip, so that the device 100 is a discrete, one-chip design.

Prior attempts to integrate a GPS receiver and electronic compassing using a

magneto-resistive sensor have typically involved at least two chips placed separately on a

printed circuit board, which likely results in a larger-sized end-user device (e.g. cell

phone, portable device, watch, etc.) and increased complexity. The one-chip design of

device 100, however, provides reduced sized and added functionality. This smaller size

may be useful in such applications as cell phones, handheld GPS units, and watches, for

example. Further, this integrated design allows a user to determine a compass heading

both while stationary and while moving. GPS (and other satellite-based systems) require

the GPS receiver to be moving at an approximate velocity of at least 10 m.p.h. relative to the surface of the earth in order to allow the GPS receiver to determine a compass

heading, based on past and present position. Thus, if used in a cell phone, for example, the one-chip design of device 100 could allow a user to determine both position and

heading while standing or walking. Other applications may include industrial or

automotive uses.

The first and second portions 102, 104 of the device 100 may be manufactured

using standard RF/microwave processes, such as CMOS, gallium-arsenide (GaAs),

germanium, BiCMOS (bipolarCMOS), InP (indium phosphide), SOI (silicon-on-

insulator), and MOI (micro wave-on-insulator). While a technology like GaAs may

provide advantages in operational speed, reduced power consumption might best be realized through the use of other techniques, such as those involving SOI (Silicon on

Insulator) or MOI (Microwave-On-Insulator), a variation of SOI. hi a prefeixed embodiment, the first portion 102 is manufactured using standard lithography,

metallization, and etch processes. The second portion 104 is preferably manufactured using Honeywell's MOI-5 0.35 micron processing, or another RF/microwave method,

such as GaAs processing. Integrating the magnetic field sensing device with the GPS receiver in a single

chip design may be accomplished in at least two ways. FIGs. IA illustrates a first

embodiment where a magneto-resistive sensor 102 is fabricated on a single die along with

the GPS receiver 104 and possibly other circuitry, such as signal conditioning and ESD

protection circuitry, for example. In the embodiment illustrated in FIG. IA, the GPS

receiver 104 and other circuitry and the magneto-resistive sensor 102 are located in

discrete layers in a single die. FIG. IB illustrates a second way in which a magnetic field sensing device can be integrated with a GPS receiver. In FIG. IB, a magneto-resistive sensor 102 is fabricated

on a first die, while the GPS receiver 104 and signal conditioning circuitry are fabricated

on a second die. The first die and the second die may then be placed in close proximity to

one another and packaged within a single integrated circuit chip 106. In all cases, it may

be advantageous to include one or more electrical connections between the GPS receiver

104 and the magneto-resistive sensor 102 to provide feedback, for example.

Alternatively, the GPS receiver 104 and magneto-resistive sensor 102 may simply be

located physically close to one another with no intentional electrical interaction. Additionally, FIG. lC. illustrates a second embodiment of a single die integration wherein a magneto-resistive sensor 102 and a GPS receiver 104 and other circuitry are

contained in a single die. However, in the embodiment illustrated in FIG. 1C, wiring 108

and the magneto-resistive sensor 102 are contained in separate portions of the second portion of the die. Some GPS receiver circuitry and signal conditioning circuitry may generate

electromagnetic fields significant enough to influence the operation of the magnetic field

sensing device. As a result, the sensitive parts of the first portion 102 of the integrated

device 100 may need to be physically separated from parts of the second portion 104 in

order to provide optimal magnetic field sensing device operation. The amount of

separation may be determined using theoretical or empirical means, for example.

As an alternative to introducing physical separation between potentially interfering

parts of the integrated device 100, a shielding layer may be provided. FIGs. 2A-2C

illustrate three exemplary configurations for such a shield. The device 200 of FIG. 2 A is

a single die integration of a magnetic field sensing device 202 and a GPS receiver 204 with a shielding layer 206 located substantially between the two. The shielding layer 206

may extend over some of or over the entire interface between the first and second portions 202, 204, depending on the characteristics of the electromagnetic fields and the location

of sensitive components. FIG. 2B illustrates a single die integrated magnetic field sensing device 202 and

GPS receiver 204 with a shielding layer 208 located within the second portion 204.

Shielding layer 208 is a localized shield which might be beneficial where the majority of

the magnetic field effects originate from a relatively small part of the second portion 204.

The shield 208 may also be advantageous in designs having electrical connections between the first and second portions 202, 204. However, shielding layer 208 could be

made less localized where necessary to properly shield sensitive components.

FIG. 2C illustrates a multiple die, integrated magnetic field sensing device 202 and GPS receiver 204 with a shielding layer 210 located substantially between the

magnetic field sensing device 202 and the GPS receiver 204. The shielding layer 210

may extend over some of or over the entire interface between the magnetic field sensing device 202 and the GPS receiver 204, depending on the characteristics of the

electromagnetic fields and the location of sensitive components. The magnetic field

sensing device 202, the GPS receiver 204, and the shielding layer 210 are contained in a

single-chip package 212. For all embodiments, use of a shielding layer will likely allow

tighter integration of the device 200 than use of physical separation of physical parts.

While such a shielding layer may comprise metal or a magnetic material (e.g. NiFe film),

other materials may also be suitable.

FIG. 3 illustrates an exemplary architecture of a device 300, in which a GPS

receiver 302 may be implemented with a magnetic field sensing device 304 on a single die. The GPS receiver circuitry (along with any signal conditioning circuitry and drivers for set and/or offset straps associated with the magnetic field sensing device portion) may

be fabricated largely within the GPS receiver underlayer 302, while a magneto-resistive

sensor 304 may be fabricated above the planar dielectric layer 306. Also shown in FIG. 3

are contacts 308 for connecting the GPS receiver underlayer 302 with the magneto-

resistive sensor 304. Additionally, NiFe permalloy structures 310 which are part of the

magneto-resistive sensor 304 are shown. i a preferred embodiment, the GPS receiver underlayer 302 may be fabricated

first. A substantially planar dielectric layer 306 (i.e. contact glass) is then deposited on the GPS receiver underlayer 302, on top of which the magneto-resistive sensor 304 is then

fabricated. The GPS receiver underlayer 302 is fabricated first because its fabrication

processes usually require the highest temperatures. Additionally, the function of the planar dielectric layer 306 is to provide a substantially planar surface on which the

magneto-resistive sensor can be fabricated, as well as to electrically isolate the GPS receiver underlayer 302 from the magneto-resistive sensor 304.

FIG. 4 illustrates a detailed view of an exemplary architecture of a device 400, in which a GPS receiver may be implemented with a magnetic field sensing device on a

single die. The GPS receiver circuitry (along with any signal conditioning circuitry and

drivers for set and/or offset straps associated with the magnetic field sensing device

portion) may be fabricated largely within the CMOS/Bipolar underlayers 402, while a

magneto-resistive sensor may be fabricated in layers 404-408, above the planar dielectric

layer 410. Also shown in FIG. 4 are various contacts V1-V3 and metallizations M1-M3,

NiFe permalloy structures, a 1^st dielectric layer 408, a second dielectric layer 406, and a

passivation layer 404. In one embodiment, layers 404-408 are formed using standard lithography, metallization, and etch processes, while layers 410 and 402 are formed using

Honeywell's MOI-5 0.35 micron processing, or another RF/microwave method, such as

GaAs processing. Other components of the magneto-resistive sensor (such as set, reset, and offset straps; signal conditioning circuitry, and ESD protection circuitry) may be

included in various locations in the layers 408-410 and 402, and are not fully illustrated in

FIG. 4.

For further information on magneto-resistive sensor designs, reference may be

made to the following patents and/or patent applications, all of which are incorporated by reference herein:

(1 U.S. Pat. No. 6,529,114, Bohlinger et al., "Magnetic Field Sensing Device" This device includes a two-axis integrated device for measuring magnetic fields

including two sensor units is formed from magneto-resistive material having a crystal

anisotropy field direction. Elements of the first of two sensors unit have a total anisotropy field in a first direction. Elements of the second sensor of the two sensors unit have a

total anisotropy field in a second direction which is perpendicular to the first direction.

Means are provided for setting a direction of magnetization in the elements of the first and

second sensor units. An output of the first sensor unit is representative of magnetic field

components perpendicular to the first direction and an output of the second sensor is

representative of magnetic field components perpendicular to the second direction.

(2) U.S. Pat. No. 6,232,776, Pant et al. ("Pant et al." "Magnetic Field Sensor for

Isotropically Sensing an Incident Magnetic Field in a Sensor Plane"

Pant et al. provides a magnetic field sensor that isotropically senses an incident

magnetic field. This is preferably accomplished by providing a magnetic field sensor

device that has one or more circular shaped magneto-resistive sensor elements for sensing the incident magnetic field. The magneto-resistive material used is preferably isotropic,

and may be a CMR material or some form of a GMR material. Because the sensor elements are circular in shape, shape anisotropy is minimized. Thus, the resulting

magnetic field sensor device provides an output that is relatively independent of the

direction of the incident magnetic . field in the sensor plane.

In one embodiment of Pant et al., the magnetic field sensor includes a first leg and

a second leg. . The first leg is connected between an output net and a first power supply

terminal. The second leg is connected between the output net and a second power supply

terminal. To sense an incident magnetic field isotropically, at least one circular shaped sensor element formed from a magneto-resistive material is incorporated into at least one

of the first and second legs. Preferably, two or more circular shaped magneto-resistive sensor elements are incorporated into either the first leg or second leg, with the other leg

formed from a non-magneto-resistive material. The two or more circular shaped sensor

elements are preferably connected in a series configuration via a number of non-magneto- resistive connectors to form the corresponding leg.

To maximize the sensitivity of the magnetic sensor device, the circular shaped

sensor elements are preferably formed from a CMR material. However, it is

contemplated that GMR materials may also be used. Illustrative CMR materials are those

generally described by the formula (LnA)MnO₃, wherein Ln=La, Nd, or Pr and A=Ca, Sr,

Ba or Pb. Preferably, the Colossal MR material is LaCaMnO, having concentrations of La

between 26-32 atomic percent, Ca between 9-20 atomic percent, and Mn between 47-64

atomic percent. hi another embodiment Pant et al., the magnetic field sensor includes a first leg, a

second leg, a third leg, and a fourth leg. The first and second legs preferably are connected between a first output net and a second output net, respectively, and a first power supply terminal. The third and fourth legs preferably are connected between the

first output net and the second output net, respectively, and a second power supply. To

sense an incident magnetic field isotropically, at least one circular shaped sensor element

formed from a magneto-resistive material is incoφorated into at least one of the first,

second, third and fourth legs. Preferably, the first and fourth legs are each formed from

two or more circular shaped magneto-resistive sensor elements, with the second and third

legs formed from a non-magneto-resistive material. For each of the first and fourth leg,

the corresponding two or more circular shaped sensor elements are preferably connected in a series configuration via a number of non-magneto-resistive connectors to form the

corresponding leg. The circularly shaped magneto-resistive sensor elements are preferably

formed from the same CMR materials as described above.

(3) U.S. Pat. No. 5,952,825, Wan ("Wan"), "Magnetic Field Sensing Device Having

Integral Coils for Producing Magnetic Fields" Wan provides both a setting/resetting feature and an independent feature of

producing a known magnetic field at the magnetic sensing elements through the use of a

unique arrangement of coils. The presence of both of these features in a magnetic field

sensor increases the sensor functionality far beyond the sum of the individual functions of

the two features. To facilitate this, Wan uses an extremely-small, low-power device that includes a

means for setting and resetting the magnetic domains in magneto-resistive sensors

arranged in an electrical bridge network, and a current strap for setting the directions of

magnetization in opposing bridge elements. The directions of the magnetization in

opposing bridge elements may be set in the same or opposite direction depending on the particular design. The current strap produces a known magnetic field at the magnetic field sensing elements. The known magnetic field is used for functions such as testing,

set up, compensation and calibration, as well as in feedback applications.

(4 U.S. Pat. No. 5,820,924. Witcraft et al.. "Method of Fabricating a

Magnetoresistive Sensor" Witcraft et al. provides a method that includes (i) fabricating a magnetic field

sensor including the steps of providing a silicon substrate; (ii) forming an insulating layer

on the substrate generating a first magnetic field as a new line; (iii) forming a layer in the

presence of said first magnetic field of magneto-resistive material on the insulating layer;

(iv) determining a first value of the anisotropy field; and (v) annealing at a temperature selected to provide a desired anisotropy field. Device" Pant et al. II provides a setting/resetting feature and an independent feature of

producing a known magnetic field at the magnetic sensing elements. The presence of both of these features in a magnetic field sensor increases the sensor functionality far

beyond the sum of the individual functions of the two features. In one aspect, Pant et al. II includes a device for setting and resetting the magnetic

domains in magneto-resistive sensing elements arranged in an electrical bridge network.

A current strap is provided for setting the directions of magnetization in opposing bridge

elements in the same direction or in opposite directions depending on the particular

design, h another aspect of the present invention, a second current strap produces a

known magnetic field at the magnetic field sensing elements. The known magnetic field is

used for functions such as testing, set up, and calibration. (6) U.S. Pat. App. No. 09/947.733. Witcraft et al. ("Witcraft et al. IPX "Method and

System for Improving the Efficiency of the Set and Offset Straps on a Magnetic

Sensor" Witcraft et al. //provides a method for manufacturing a magnetic field sensor that

includes the step of providing a keeper material proximate to a magnetic field sensing

structure. The sensor includes a substrate, a current strap, and the magnetic field sensing

structure. Witcraft et al. II also provides either a set-reset strap or an offset strap as the

current strap. This embodiment may also include both a set-reset strap and an offset strap

in the same sensor, hi another embodiment, the magnetic field sensing structure also includes Permalloy strips electrically connected to one another and to an output terminal,

where a magnetic field indication is produced.

(7) U.S. Pat. App. No. 10/002,454, Wan et al. ("Wan et al. IP titled "360-Degree

Rotary Position Sensor" In Wan et al. II, the 360-degree rotary position sensor is comprised of a Hall

sensor and a magneto-resistive sensor. Either a magnet or the 360-degree rotary position

sensor is mounted on a rotating shaft. The 360-degree rotary position sensor is located

substantially close to the magnet, so that the 360-degree rotary position sensor is capable

of detecting a magnetic field produced by the magnet. The Hall sensor detects a polarity

of the magnetic field. The magneto-resistive sensor detects an angular position of the

magnetic field up to 180-degrees. A combination of an output from the Hall sensor and

an output from the magneto-resistive sensor provides sensing of the angular position of

the magnetic field up to 360-degrees. (8) U.S. Pat. No. 5,521.501. to Dettmann et a " Dettmann et al."), titled "Magnetic

Field Sensor Constructed from a Remagnetization Line and One Magnetoresistive

Resistor or a Plurality of Magnetoresistive Resistors" Dettmann et al. provides a single magnetic-field-dependent resistor comprising

one or a plurality of magneto-resistive film strips on a highly-conductive thin-film

conductor strip disposed peφendicular to the longitudinal direction of the magnetic-field-

dependent resistor in an insulated manner. The highly-conductive thin-film conductor strip is provided with a meandering structure. To create a resistance under current flow,

in spite of the meandering strips of alternating magnetic field direction which are disposed adjacent to each other with the resistance changing equidirectionally in all subranges

under the influence of a field that is to be measured, the magneto-resistive film strips are

divided into regions having Barber pole structures with an angle of inclination that is

opposite to the longitudinal direction of the strip. Advantageously, the meandering of the highly-conductive thin-film conductor

strip results in the fact that only a little current is needed for the reversal of the direction of magnetization. Furthermore, the stray magnetic field existing outside of the sensor

chip is very low because the magnetic fields of the meandering strips that are disposed

adjacent to each other largely cancel each other because of their opposing direction.

Thus, the magnetic field sensors can be operated in immediate proximity to each other.

For that same reason, the remagnetization conductor also has a very low inductance, so

that limitations of the measuring frequency due to the inductance no longer occur.

When the magnetic field sensor is operated with a magneto-resistive resistor, the

latter is fed with a constant current. The voltage at the magneto-resistive resistor is

measured as an output signal. Following a current pulse of a certain direction through the highly-conductive thin-film conductor strip, the self-magnetization in the areas of the magneto-resistive resistor is set in a certain manner, hi this state, the magnetic field that

is to be measured causes an increase of the resistance value of the magneto-resistive

resistor. This means that the output signal is greater than in the case without a magnetic

field. If a current pulse of opposite direction to the previous pulse is now fed into the

highly-conductive thin-film conductor strip, the directions of the self-magnetizations are

reversed. Thus, the field that is to be measured causes a reduction in the resistance and

the output voltage is smaller than in the case without a magnetic field. With a constantly changing pulse direction, an AC voltage whose amplitude is proportional to the magnetic

field to be measured is thus present at the output. Any influences, such as the temperature leading to a slow drift of the resistance value of the magneto-resistive film strip, do not

influence the AC output voltage. But the decrease of the magneto-resistive effect is

perceptible as the temperature in the output AC voltage amplitude increases. Therefore, a further, highly-conductive film strip is provided under every

magneto-resistive film strip in another embodiment. The current through these highly-

conductive film strips is controlled by the sensor output voltage such that the applied

magnetic field to be measured is just cancelled by the current. In this case, the magneto¬

resistive magnetic field sensor acts as a zero detector. The output quantity of the

arrangement is the quantity of the compensation current, which is not dependent on the

temperature of the arrangement. Likewise, non-linearities no longer play a role in the

sensor characteristic curve, because the sensor is not modulated.

In a further embodiment of Dettmann et al, four parallel magneto-resistive

resistors, each comprising a plurality of regions, are provided above the thin-layer

remagnetization conductor and the highly-conductive compensation conductor. The regions are provided with Barber pole structures of an alternating positive and negative angle from the longitudinal direction of the magneto-resistive film strip such that they respectively begin with alternating regions of a positive and negative Barber pole structure angle. The four resistors are connected to form a Wheatstone bridge. If the remagnetization conductor is again operated with pulses of altematingly opposite directions, an AC voltage signal appears at the bridge output. Only one direct voltage signal, which results from the possibly non-identical four resistance values of the bridge, is supeφosed over this signal. This direct voltage component is, however, significantly smaller than in the use of a single resistor, which permits simpler evaluation. Of course, the compensation of the magnetic field to be measured can also be employed here. The bridge arrangement can comprise four resistors formed from an even number of regions. Only the sequence of the angle of the Barber pole structure changes from one resistor to the other. The remagnetization direction is set in the regions by a first, strong current pulse through the remagnetization conductor. The sensor bridge is thus magnetic field-sensitive, and can be used in a conventional manner without further remagnetization. Because all four resistors of the bridge comprise identical regions, identical changes are to be expected in all resistors when the temperature of the sensor arrangement is variable. This also applies for the change component that arises because of the variable layer voltages and, subsequently, because of the magnetostriction. The sensor bridge therefore has a reduced zero point compared to known sensor bridge arrangements, and is therefore also suited for measuring smaller fields in conventional operation. A constant current through the remagnetization conductor can serve to generate a certain stabilization magnetic field, via which a certain sensor sensitivity is set. The arrangement of Dettmann et al, therefore, can be used advantageously in the application of different evaluation methods for magnetic field measurement.

FIG. 5 illustrates a plan view of one embodiment of a device 500 in which a GPS

receiver is integrated with a magnetic field sensing device on a single die. The structures

visible in FIG. 5 are attributable largely to a magneto-resistive sensor (and other circuitry,

such as set/offset drivers or magnetic sensor signal conditioning circuitry formed in the

underlayers of the device 500). Exemplary parts of the device 500 include a magnetoresistive bridge 502, set/reset straps 504, offset straps 506, set/reset circuitry 508, 510,

laser trim sites 512 (for matching impedance of the legs of the magneto-resistive bridge

502), ESD protection diode 514, operational amplifiers 516, contacts 518, test sites 520, and GPS receiver components 522. Reference may be made to the patents and patent

applications incoφorated above for further information.

FIG. 6 is a simplified block diagram of a GPS receiver 600. The GPS receiver 600 receives signals 602 from at least three different GPS satellites received by an

antenna on the device. The received signals 602 are then usually filtered by a passive

bandpass prefilter 604 to reduce out-of-band RF interference and preamplified 604. Next,

the RF signals are typically downconverted to an intermediate frequency (IF) 606, and

converted from analog to digital 606. These signals are then sent to the digital signal

processor (DSP) 608. From the DSP 608 the signal undergoes navigation processing 610,

which yields position, velocity, and time information 612. Because conventional

processes are used, the particular GPS circuitry is not disclosed herein, as it is flexible.

Thus, conventional GPS receiver designs implementable in CMOS/GaAs/BiCMOS, for

example, can be utilized in accordance with the presently disclosed embodiments. FIG. 7 illustrates one application 700 for the integrated GPS receiver and magnetic field sensing device set forth herein. A user 702 is shown with a cell phone 704 having a single-chip integrated GPS receiver and magnetic field sensing device. The user 702 is able to obtain location and heading information by orienting the cell phone 704 in the direction the user 702 is facing, for example. The magnetic field sensing device is able to determine direction while the GPS receiver is able to determine the user's 702 location. The combination provides synergistic effects, such as the ability to perform database lookups to combine directions with yellow page information. For example, a user 702 could obtain a phone number for a business or residence the user is facing by causing the cell phone 704 to transmit location and heading information to a network server, which could respond with the phone number.

FIG. 8 illustrates another application 800 for the integrated GPS receiver and magnetic field sensing device set forth herein. A user 802 is show with a video camera 804 having a single-chip integrated GPS receiver and magnetic field sensing device. The user 802 is able to obtain location and heading information by orienting the video camera 804 in the direction the user is facing. The magnetic field sensing device is able to tell the user 802 what direction he is facing, while the GPS receiver is able to determine the user's 802 location. The combination provides synergistic effects, such as the ability to record location and heading information which correlates to the footage being recorded by the user 802. This could allow the user 802 to later identify buildings or other landmarks that that were recorded, as well as allow the user 802 to later find the same area where particular footage was recorded. Of course, many other uses are possible as well. Because only one chip is needed, rather than two or more, the overall size of the user's 802 device (e.g. digital camera, cell phone, portable device, watch, etc.) may be kept

small.

Table 1, below, shows a simplified exemplary process for integrating a GPS

receiver with a magnetic field sensing device. It is believed that such a process is unique

because, in the past, semiconductor foundries have gone to great lengths to prevent

contamination of their processes with materials typically used in manufacturing magnetic

sensors, hi addition, companies in the magnetic industries (e.g. disk drive head

manufacturers, etc.) have' been separate from electronics companies, and their specialized manufacturing techniques have been kept largely separate from one another. TABLE 1: Sample Manufacturing Process

CMOS, Bipolar, GaAs, BiCMOS, InP, SOI, MOI underlayers

(end front-end processing; begin back-end processing)

Deposit contact glass (if any), reflow

Foi magnetic field sensing device layer

Inspection and evaluation

In a preferred embodiment, the semiconductor device processing (i.e. CMOS,

Bipolar, GaAs, etc.) is done at the front end, while the metal interconnect and the

magnetic field sensing device are done at the back end. Table 1 is intended to be

generally applicable to any magnetic field sensing device manufacturing process, and thus

does not include detail on how to obtain particular architectures. Additional cleaning and

other steps should be implemented as appropriate.

An exemplary embodiment of the present invention has been described above.

Those skilled in the art will understand, however, that changes and modifications may be made to this embodiment without departing from the true scope and spirit of the present invention, which is defined by the claims.

Claims

What is claimed is: 1. A single package sensor device comprising: GPS receiver circuitry; and at least one magnetic field sensing device adjacent to the GPS receiver circuitry.

2. The sensor device of claim 1 wherein the at least one magnetic field

sensing device comprises a sensor selected from one of the group consisting of a

compassing sensor, an anisotropic magneto-resistive (AMR) sensor, a giant magnetoresistive (GMR) sensor, a colossal magneto-resistive (CMR) sensor, a hall effect sensor, a

fluxgate sensor, and a coil sensor.

3. The sensor device of claim 1 wherein the GPS receiver circuitry and the at least one magnetic field sensing device are monolithically formed on a single die.

4. The sensor device of claim 3 wherein a dielectric layer is disposed between

the GPS receiver circuitry and the at least one magnetic field sensing device.

5. The sensor device of claim 3 wherein the at least one magnetic field

sensing device is formed using standard fabricating processes for forming magneto¬

resistive sensors.

6. The sensor device of claim 3 wherein at least one shield is disposed between the GPS receiver circuitry and the at least one magnetic field sensing device.

7. The sensor device of claim 3 wherein the at least one magnetic field sensing device is used for electronic compassing.

8. The sensor device of claim 1 wherein the GPS receiver circuitry and the at

least one magnetic field sensing device are formed in at least two separate die, all die being contained in a single-chip package.

9. The sensor device of claim 8 wherein the at least one magnetic field

sensing device is formed using standard fabricating processes for forming magnetoresistive sensors.

10. The sensor device of claim 8 wherein at least one shield is disposed between the GPS receiver circuitry and the at least one magnetic field sensing device.

11. The sensor device of claim 8 wherein the at least one magnetic field sensing device is used for electronic compassing.

12. A method for making a sensor device, the method comprising the steps of: forming GPS receiver circuitry; and forming at least one magnetic field sensing device adjacent to the GPS receiver circuitry; wherein the GPS receiver circuitry and the at least one magnetic field

sensing device are formed into a single package.

13. The method of claim 12 wherein the step of forming the at least one

magnetic field sensing device includes forming the at least one magnetic field sensing

device from a sensor selected from one of the group consisting of a compassing sensor, an

anisotropic magneto-resistive (AMR) sensor, a giant magneto-resistive (GMR) sensor, a

colossal magneto-resistive (CMR) sensor, a hall effect sensor, a fluxgate sensor, and a

coil sensor.

14. The method of claim 12 further comprising forming the GPS receiver

circuitry and the at least one magnetic field sensing device on a single die.

15. The method of claim 14 further comprising depositing a dielectric layer

between the GPS receiver circuitry and the at least one magnetic field sensing device, wherein the dielectric layer is deposited on the GPS receiver circuitry before the at least

one magnetic field sensing device is formed.

16. The method of claim 14 further comprising forming at least one

electromagnetic shield between the GPS receiver circuitry and the at least one magnetic

field sensing device.

17. The method of claim 12 further comprising forming the GPS receiver circuitry and the at least one magnetic field sensing device in at least two separate die, all

die being contained in a single-chip package.

18. The method of claim 17 further comprising forming at least one electromagnetic shield between the GPS receiver circuitry and the at least one magnetic

field sensing device.

19. A single package sensor device comprising: GPS receiver circuitry formed from any of complementary-metal-oxide- semiconductor (CMOS), gallium-arsenide (GaAs), germanium, bipolarCMOS (BiCMOS), indium phosphide (InP), silicon-on-insulator (SOI), and microwave- on-insulator (MOI) technologies; and at least one magnetic field sensing device adjacent to the GPS receiver circuitry, the at least one magnetic field sensing device comprising a sensor selected from the group consisting of a compassing sensor, an anisotropic magneto-resistive (AMR) sensor, a giant magneto-resistive (GMR) sensor, a colossal magneto-resistive (CMR) sensor, a hall effect sensor, a fluxgate sensor, and a coil sensor; wherein the GPS receiver circuitry and the at least one magnetic field sensing device are monolithically formed on a single die with contact glass disposed between the GPS receiver circuitry and the at least one magnetic field sensing device and with at least one conductive connection pathway in the contact glass for connecting the GPS receiver circuitry with the at least one magnetic field sensing device; wherein at least one shield comprising a material selected from the group consisting of metal, magnetic material, and other isolating material is disposed between the GPS receiver circuitry and the at least one magnetic field sensing device; and wherein the at least one magnetic field sensing device is used for electronic

compassing.