Transcript PT for STM

1. Microgate 6D Module (6X Sensor)
■ 6D module : One Chip with 3D Magnetometer & 3D Accelerometer

3MAG channels & 3ACC channels

±2g / ±8g ACC full scale

2.6V to 3.3V supply voltage

2° resolution of ACC

Max. 1.0mA current consumption

I2C serial interface

±3 gauss MAG full scale

Power down mode

3° resolution of E-compass

4.4 x 7.5 x 1.1 (mm)

No user calibration of E-compass

LGA 16 pin
■ Composition of 6D module
3D Magnetometer
3D Accelerometer
(Microgate)
(STM)
Thin Film
Fluxgate Sensor
( 6 inch wafer MP )
ASIC for MAG
X-sensor
Y-sensor
Z-sensor
1
MEMS
Capacitive type
ASIC for ACC
MEMS
element
( 8 inch wafer MP )
PCB
ⓒ 2006 microgate, Inc., All rights reserved.
microgate, Inc.
2. Thin Film Fluxgate Sensors for E-compass
■ Operation Principle of Fluxgate Sensors
X & Y sensor
items
Z sensor
1 bar type (Cf. conventional, 2 bar type)
4 block type ( Invention of new design )
Schematic
diagram
D
P
P
D
Voltage peak height (mV) : 14 ± 1
 Peak movement quantities : over ± Δ60

Electronic
properties
Voltage peak height (mV) : 14 ± 1
 Peak movement quantities : over ± Δ20

Triangular wave (± 2V)
into the fluxgate sensor
Pick-up voltage output
from the fluxgate sensor
2
ⓒ 2006 microgate, Inc., All rights reserved.
microgate, Inc.
3. Features of Microgate E-compass
■ No User Calibration
• Thin film fluxgate sensor can detect the absolute magnetic field quantities unlike other magnetic
sensors ( Hall, MI, AMR, GMR ), which measure the relative difference values.
• The magnetic field changes according to
the location changes can be easily
calibrated by an auto-calibration S/W.
Microgate E-compass VS
High
• Only ‘One time calibration’ is required
at the electronic device manufacturers
for the calibration of the magnets or
magnetic field in the electronic devices.
Others
Low
Absolute
zero point
■ Provision of the Best & the Optimized Resolution
• 100 cardinals resolution is possible.
• The regulation of the cardinal points is, of course, possible. (Ex. ; 120, 64, 32, 16, 8, 4 cardinals)
■ Reliable Accuracy
• Fluxgate e-compass can recognize the magnetic north pole at every moment, regardless of
the location changes, temperature changes, and working time passage.
3
ⓒ 2006 microgate, Inc., All rights reserved.
microgate, Inc.
4. Direction Decision Algorithm
Final direction
information
5D(/6D) operating S/W
for the posture
compensation of
the cars & the phones
This operation is carried out
by using our providing S/W,
which will be embedded
in the host CPU
Primary direction
information
3D MAG operating S/W
XMAG
YMAG
ZMAG
Inclination & Tilt
information of 6D module
or electronic device
XACC
3D Magnetometer
YACC
ZACC
3D Accelerometer
6D Module
4
The output data form is
the numeric angle values, ‘θ’,
between the magnetic north pole
and the base line of the chip
(or the electronic devices)
ⓒ 2006 microgate, Inc., All rights reserved.
6 data serial output through I2C
interface after power on
microgate, Inc.
5. Applications of 6D Module
■ Mobile Phone & Navigator
Navigation
(Real-time direction
information)
Motion
controlled
game
Menu scroll
& Document
browsing
Camera
image
stabilization
Pedometer
Motion
dialing
■ Functional Systems
• Robot control : Robot for industry and consumer electronics
• Space data input device : Presenter (TV & PC), Mouse
• Optical image stabilization : Digital camera, Vehicle camera
• Others ; Fee-fall protections, Anti-theft application, etc.
※ In case of motion detection application, the separate algorithm developments are required.
5
ⓒ 2006 microgate, Inc., All rights reserved.
microgate, Inc.
A. The Comparison of the 6D & 3D Modules
Modules
Maker
6D module
3D module
Microgate
Asahi-Kasei
Aichi steel
Yamaha
Alps
Model number
MG33MA2DL (6D)
AKM8976A (6D)
AMI601 (6D)
MS-3C (3D)
--- (3D)
Composition
3D MAG (Fluxgate)
+ 3D ACC (Capa.)
3D MAG (Hall)
+ 3D ACC (Piezo)
3D MAG (Ml)
+ 3D ACC (Piezo)
3D MAG (GMR)
only
3D MAG (GMR)
only
Resolution ( # / 360°)
Min 100
Max 32~20
Max 32~20
Max 64~32
Not released
User’s action calibration
before using e-compass
No need
Motion added calibration and S/W (such as S/W auto calibration
DOE algorithm) are inevitably needed for the However, incorrect
finding of the reference point or reset point
& incorrigible
Not released
Thermometer for
direction calibration
No need
Built-in thermocouple is necessary for the calibration of a relative
electronic mobility flow changes in the Hall, MI, & GMR sensors
according to the temperature changes
Not released
ACC measure range (g)
±2 & ±8 selectable
±2.5
±2
-
-
ACC sensitivity (mg/bit)
18 & 72
20
2.5
-
-
Current consumption
(mA)
Max 1.0
Max 9.7
Max 30
Max 4 (e-compass)
Not released
Chip size
4.4 x 7.5 x 1.1
4.5 x 4.5 x 1.0
5.2 x 6.0 x 1.6
2.0 x 2.0 x 1.0
3.5 x 3.5 x 1.0
PKG
Plastic PKG
14 pin LGA
Ceramic PKG
20 pin LCC
Vacuum PKG
14 pin
Plastic PKG
10 pin CSP
Plastic PKG
10 pin LGA
CPU
Not included
CPU usage
CPU usage
Not included
Not released
Interface
I2C
I2C & SPI
I2C
I2C
I2C
Chip shape
6
ⓒ 2006 microgate, Inc., All rights reserved.
microgate, Inc.
B. Calibrations We Have To Control
No
The cause of perturbation
1
The misfit between the true north
pole & the magnetic north pole
(Longitude & Latitude)
2
Horizontal magnetic field intensity
changes according to the latitude
(equator ~ through ~ each pole)
3
Location
User’s environment
(indoor, outdoor, underground,
in a car, etc.)
Solutions

Simple map-tilt on the monitor display
according to the DB of customer’s location
(, which can be selected by users)

The 3-D e-compass detect the vector sum
of an earth’s magnetic field at any places
 Therefore, not serious problem
 If change exist  auto calibration possible

Real time magnetic field intensity measurement
by using our S/W is possible
 Auto calibration can minimize the error
occurrence

4
Permanent magnets in the phone
(ear phone, vibration motor, wake-up)
The magnetic fields from each magnet are
not too high to influence our e-compass
 It’s possible to calibrate the effects at the
phone makers

5
7
E-compass, itself
Fundamentally, the fluxgate sensors do not
make an accumulative error in itself.
This is the most important reason why we
have selected the fluxgate sensors for our
e-compass products, since 2002
ⓒ 2006 microgate, Inc., All rights reserved.
microgate, Inc.
C. Earth’s Magnetic Field Distribution
8
ⓒ 2006 microgate, Inc., All rights reserved.
microgate, Inc.
D. Magneto-Impedance Sensor
■ MI Sensor (Aichi steel)

When high frequency applied along the wire, the surface of wire
becomes insulator. It is called skin depth effect.

MI use skin depth changes of wire surface which can be varied by
the external magnetic field changes.
9

MI has a reliability problem of the voltage output position.

And, Uniformity of the every wire surface structure must be guaranteed.

MI sensor is a bulk assembled sensor  MP speed & Yield decrease.

Z-sensor height problem  thick chip

High frequency usage  Noise occurrence
ⓒ 2006 microgate, Inc., All rights reserved.
microgate, Inc.
E. Hall-effect Sensor
■ Hall Sensor (Asahi-Kasei)

The Hall sensor can check the voltage difference (VH) in the semiconductor Hall films.
The Hall voltages are made by charging up of electrons due to the magnetic field application.

The measured VH is not an absolute value, but relative values.
Therefore, zero point reset of output voltage is required, for it being used as an e-compass.
The requirement of DOE algorithm suggested by Asahi-Kasei and motion added calibration represent that
Hall can not find the zero point or reference point of the magnetic field, if it were not for ceaseless calibration.
10

Hall also need temperature compensation because the increase of temperature increases the electron motilities.

The partition of the Hall voltage difference is not accurate.  Therefore, the resolution power is not high.
ⓒ 2006 microgate, Inc., All rights reserved.
microgate, Inc.
F. Anisotropic Magneto-Resistive Sensor
■ AMR Sensor (Honeywell)
Major
loop
R2
R3
R4
Circuit
R1
R = R0 + ΔR0 cos2 θ
Minor
loop

The MR effect means the resistance drop of the NiFe films according to the existence of the extra magnetic field.
The AMR film must be made to have a directional magnetization by applying high magnetic field.
When the external magnetic field (ex. The earth’s magnetic field) is applied with an angle (θ), the magnetization
direction in the film is rotated.
In this case, the resistance of the film decrease and the resistance changes is around -2%.
 The resistance changes (~10-6 order) has the relation with the external magnetic field indirectly.
 This is the operating principle of the AMR sensor.
<Problems of AMR sensor>
 It must be maintained the initial directional magnetization of the NiFe films, however, it diverge as times goes by.
When times goes by, or temperature increases, the directional magnetization lose its directionality, therefore,
calibration and additional magnetization reset is required.
 According to Honeywell, high volt (~40 volt) is required by using a solenoid coil in the AMR sensor for renew reset.
 The usage of minor loop.  The trace of the minor loop is not reproducible.  Reliability decrease and calibration
required
11
ⓒ 2006 microgate, Inc., All rights reserved.
microgate, Inc.
G. Giant Magneto-Resistive Sensor
■ GMR Sensor (Alps, Yamaha, Hitachi)
Top Electrode (Ta or Ru)
CoFe/NiFe, CoFe, NiFe
Cu
CoFe
Anti-Ferro Magnet (IrMn, PtMn)
Under Layer (NiFe)
Bottom Electrode (Ta)
Si Wafer
Operating
principle
GMR Sensor
vertical structure
Signal output
(Resistivity change)

GMR is also operated by changing the magnetization direction in the film like an AMR.
 At initial stage, the spin directions of two magnetic layers are anti-parallel.
 When the external magnetic field is applied on GMR films as shown in the 2 nd figure, the magnetization align
parallel. In this case, the resistance decrease.
<Problems of GMR sensor>
 Almost the same problems of the previous mentioned AMR sensor still exist in GMR sensor.
If GMR can notice the absolute 0 value of the magnetic field, there will be no need of using auto calibration S/W.
The existence of the auto calibration S/W implies that GMR also can not measure the absolute value of the
magnetic field
 The resolution of GMR is higher than that of AMR, because the MR ratio of GMR is 10%~40% according to the
manufacturing technology. (Cf. MR ratio of AMR is around 2%)
12
ⓒ 2006 microgate, Inc., All rights reserved.
microgate, Inc.
H. Conventional Fluxgate Sensor
■ Conventional 2-bar Type Fluxgate Sensor
■ PCB Fluxgate Sensor (Samsung, AP1systems)
NiFe bar

13
Bulk assembled sensor  Z-sensor manufacturing of short height is impossible.
ⓒ 2006 microgate, Inc., All rights reserved.
microgate, Inc.
I. Magnetic Properties of Thin Film Fluxgate
■ The Origination of Isolated Peak & Peak Shift in Microgate’s Fluxgate Sensor
Hs
Hc
Peak positions
without any external
magnetic field
time

The hysteresis loop with extremely high squareness
at e-compass operation frequency (12KHz)
is absolutely required.
 Small coercivity (Hc) & Fast saturation (Hs) at high
frequency range is needed to make an isolated peak.
 Voltage peak height = - η•(dM/dt)
 If the inclination of loop decrease slightly, (dM/dt)
decrease drastically and voltage peak finally disappear.
 fluxgate become a kind of transformer like bulk
or PCB fluxgate
Peak shift according to the (+)DC magnetic field
(DC magnetic field means the earth’s magnetic field)
Peak shift according to the (-)DC magnetic field
time
14
ⓒ 2006 microgate, Inc., All rights reserved.
microgate, Inc.
J. Output Signal Changes due to the Applied Magnetic Field
■ Peak Shift Occurrence due to the External Magnetic Field
Isolated voltage peak shift
Applied field
( +1.0 gauss )

Peak-to-peak distance (scale : µsec) can
be measured by using ASIC.
C

The real earth’s magnetic field is around
±0.5 gauss.

When the earth’s magnetic field is applied
on the fluxgate, the peak shift distance will
No external field
(standard state)
be the half of the peak shift distance shown
in photograph. (±1.0 gauss were applied
A
to make it easy to notice).
Applied field
(-1.0 gauss)
Magnetic field detection range

B
~±1.0 gauss
The detection range can be changed
by changing the fluxgate design.
~±3.5 gauss
15
ⓒ 2006 microgate, Inc., All rights reserved.
microgate, Inc.
K. Block Diagrams of 6D module
■ 3D E-compass
■ 3D Accelerometer
16
ⓒ 2006 microgate, Inc., All rights reserved.
microgate, Inc.