The document discusses sensors for low level signal acquisition and advanced signal processing techniques. It begins with a legal disclaimer stating that the presentation materials are the property of ADI and various intellectual property rights and exclusions of warranties. The document then provides an overview of topics including sensors as the source of low level signals, the importance of signal conditioning, integrating sensors with conditioning in silicon, and applications requiring higher accuracy. It provides examples of temperature, pressure, and motion sensors and discusses challenges in designing sensors in silicon.

1. Sensors for Low Level Signal
Acquisition
Advanced Techniques of Higher Performance Signal Processing

2. Legal Disclaimer
 Notice of proprietary information, Disclaimers and Exclusions Of Warranties
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INFORMATION AND THE ADI PRESENTATION TO BE ACCURATE, NO WARRANTIES OF ANY KIND ARE MADE
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©2013 Analog Devices, Inc. All rights reserved.
2

3. Today’s Agenda
Sensors are the source
Sensor signals are typically low level and difficult
Signal conditioning is key to high performance
Silicon sensors are integrated with signal conditioning
Applications keep demanding higher accuracy
Motion sensors with moving silicon elements are driving systems in
all market areas
3

4. The Goal
Capture what is going on in the real world
Convert into a useful electronic format
Analyze, manipulate, store, and send
Return to the real world
4

5. The Real World Is NOT Digital
5

6. Analog to Electronic Signal Processing
6
SENSOR
(INPUT)
DIGITAL
PROCESSOR
AMP CONVERTER
ACTUATOR
(OUTPUT)
AMP CONVERTER

7. The Sensor
7
SENSOR
(INPUT)
DIGITAL
PROCESSOR
AMP CONVERTER
ACTUATOR
(OUTPUT)
AMP CONVERTER
Analog, but
NOT electronic
Analog
AND electronic

8. Popular Sensors
Sensor Type Output
Thermocouple Voltage
Photodiode Current
Strain gauge Resistance
Microphone Capacitance
Touch button Charge output
Antenna RF signals
Acceleration Capacitance
8

9. Sensor Signal Conditioning
9
SENSOR AMP
Analog, electronic,
but “dirty”
Analog, electronic,
and “clean”
 Amplify the signal to a noise-resistant level
 Lower the source impedance
 Linearize (sometimes but not always)
 Filter
 Protect

10. Designing Sensors in Silicon
Sensor signals are typically low level and subject to
noise coupling on connections to amplifiers
Bring signal conditioning as close to sensor as possible
 Multichip hybrids
 Silicon sensor on same chip as amplifier/data converter
Environmental issues
 Extreme temperature or vibration
 Sensor needs to be small for sensitivity
Finding silicon property that responds to physical variable
 Capacitance, stress, temperature change
10

11. Silicon Sensors
Sensor Type Output
Temperature Voltage/current
Photodiode Current
Strain gauge Resistance
Microphone Capacitance
Rotation Capacitance
Antenna RF signals
Acceleration Capacitance
11

12. Types of Temperature Sensors
12
THERMOCOUPLE RTD THERMISTOR SEMICONDUCTOR
Widest Range:
–184ºC to +2300ºC
Range:
–200ºC to +850ºC
Range:
0ºC to +100ºC
Range:
–55ºC to +150ºC
High Accuracy and
Repeatability
Fair Linearity Poor Linearity Linearity: 1ºC
Accuracy: 1ºC
Needs Cold Junction
Compensation
Requires
Excitation
Requires
Excitation
Requires Excitation
Low-Voltage Output Low Cost High Sensitivity 10mV/K, 20mV/K,
or 1µA/K Typical
Output

13. Basic Relationships for Semiconductor
Temperature Sensors
13
IC IC
VBE VN
∆VBE VBE VN
kT
q
N= − = ln( )
VBE
kT
q
IC
IS
=





ln 





=
S
C
N
IN
I
q
kT
V
×
ln
INDEPENDENT OF IC, IS
ONE TRANSISTOR
N TRANSISTORS

14. Classic Band Gap Temperature Sensor
14
"BROKAW CELL"R R
+
I2 ≅ I1
Q2
NA
Q1
A
R2
R1
VN VBE
(Q1)
VBANDGAP = 1.205V
+VIN
VPTAT = 2
R1
R2
kT
q
ln(N)
∆VBE VBE VN
kT
q
N= − = ln( )

15. Analog Temperature Sensors
15
Product
Accuracy
(Max)
Max Accuracy
Range
Operating
Temp
Range
Supply
Range
Max
Current Interface Package
AD590 ±0.5°C
±1.0°C
25°C
−25°C to +105°C
−55°C to
+150°C
4 V to 30 V 298 µA Current out TO-52, 2-
lead FP,
SOIC, Die
AD592 ±0.5°C
±1.0°C
25°C
−55°C to +150°C
−25°C to
+105°C
4 V to 30 V 298 µA Current out TO-92
TMP35 ±2.0°C 0°C to 85°C
−25°C to +100°C
−55°C to
+150°C
2.7 V to 5.5 V 50 µA Voltage out TO-92,
SOT23,
SOIC
TMP36 ±3.0°C −40°C to +125°C −55°C to
+150°C
2.7 V to 5.5 V 50 µA Voltage out TO-92,
SOT23,
SOIC
AD221100 ±2.0°C −50°C to +150°C −55°C to
+150°C
4 V to 6.5 V 650 µA Voltage out TO-92,
SOIC, Die
AD22103 ±2.5°C 0°C to +100°C 0°C to
+100°C
2.7 V to 3.6 V 600 µA Voltage out TO-92,
SOIC

16. Digital Temperature Sensors Comprehensive
Portfolio of Accuracy Options
16
Product Accuracy (Max)
Max Accuracy
Range
Interface Package
ADT7420/ADT7320
±0.2°C
±0.25°C
−10°C to +85°C
−20°C to +105°C
I2C/SPI LFCSP
ADT7410/ADT7310 ±0.5°C −40°C to +105°C I2C/SPI SOIC
ADT75
±1°C (B grade)
±2°C (A grade)
0°C to 85°C
−25°C to +100°C
I2C MSOP, SOIC
ADT7301
±1°C 0°C to 70°C
SPI SOT23, MSOP
TMP05/TMP06
±1°C 0°C to 70°C
PWM SC70, SOT23
AD7414/ADT7415
±1.5°C −40°C to +70°C
I2C SOT23, MSOP
ADT7302 ±2°C 0°C to 70°C SPI SOT23, MSOP
TMP03/TMP04
±4°C
−20°C to +100°C PWM TO-92, SOIC, TSSOP

17. High Accuracy Temperature Sensing
Applications
Scientific, medical and aerospace Instrumentation
 Medical equipment
 Laser beam positioners
Test and measurement
 Calorimeters
 Automatic test equipment
 Mass spectrometry
 Thermo cyclers/DNA analyzers
 Infrared imaging
 Data acquisition/analyzers
 Flow meters
Process control
 Instruments/controllers
Critical asset monitoring
 Food and pharmaceutical
Environmental monitoring
17
17

18. Digital IC RTD Thermistor
Ease of Use
Sensor selection and
sourcing
Reliable supply and
specifications
Need to determine reliable
suppliers (specifications std.)
Need to determine reliable
suppliers and specifications
Extra signal processing
Additional sourcing,
selection, design,
evaluation, testing,
manufacturing
No
Precision ADC (≥16 bits)
Current source
Amp (optional)
Precision resistor
Filter caps
ADC (resolution is app specific)
Current source
Amp (optional)
Precision resistor
Filter caps
Linearization No Yes Yes
Calibration No Yes Yes
Resistance concerns No Yes Yes
Self heating concerns No Yes Yes
Reliability Contact resistance No Susceptible Susceptible
Batch variation No Susceptible Susceptible
Transmission noise No Susceptible Susceptible
Performance Accuracy range Industrial Range Wide range Commercial range
Stability High High Low
Repeatability High High Low
High Performance Temperature Measurement
Sensor Comparison
d
18

19. High Accuracy Temperature Measurement
Sensor Comparison
Sensor Type NTC Thermistor
PT100 RTD
(Thin Film)
Digital IC
ADT7X20
*Accuracy
±0.1°C from 0 to 70°C
±0.3°C from 0 to 100°C
Excludes:
Data conversion
Signal conditioning
Self heating, noise, drift etc.
±0.27°C from 0 to 100°
(Class 1/3 B)
Excludes:
Data conversion
Signal conditioning
Self heating
Lead wire resistance
Noise, etc.
±0.2°C from −10 to +85°C
±0.25°C from −20 to +105°C
Linearity Poor Medium to high High
Thermal response Medium to fast Medium to fast Medium to fast
Long term stability/reliability Low Medium to high High
System cost
High for low tolerance
(±0.1/0.2°C)
High Low
Calibration required Yes Yes No
Extra components required Yes Yes No
19
*For thermistors and RTDs actual tolerances will degrade in assembled system.

20. Thermocouple
Very low level (µV/ºC)
Nonlinear
Difficult to handle
Wires need insulation
Susceptible to noise
Fragile
20

21. Common Thermocouples
21
Junction Materials
Typical Useful
Range (°C)
Nominal
Sensitivity
(µV/°C)
ANSI
Designation
Platinum (6%)/Rhodium-
Platinum (30%)/Rhodium
38 to 1800 7.7 B
Tungsten (5%)/Rhenium-
Tungsten (26%)/Rhenium
0 to 2300 16 C
Chromel-Constantan 0 to 982 76 E
Iron-Constantan 0 to 760 55 J
Chromel-Alumel −184 to +1260 39 K
Platinum (13%)/Rhodium-
Platinum
0 to 1593 11.7 R
Platinum (10%)/Rhodium-
Platinum
0 to 1538 10.4 S
Copper-Constantan −184 to +400 45 T

22. Thermocouple Output Voltages
for Type J, K, and S Thermocouples
22
-250 0 250 500 750 1000 1250 1500 1750
-10
0
10
20
30
40
50
60
THERMOCOUPLEOUTPUTVOLTAGE(mV)
TEMPERATURE (°C)
TYPE J
TYPE K
TYPE S
-250 0 250 500 750 1000 1250 1500 1750
-10
0
10
20
30
40
50
60
THERMOCOUPLEOUTPUTVOLTAGE(mV)
TEMPERATURE (°C)
TYPE J
TYPE K
TYPE S

23. Thermocouple Seebeck Coefficient vs.
Temperature
23
-250 0 250 500 750 1000 1250 1500 1750
0
10
20
30
40
50
60
70
SEEBECKCOEFFICIENT-µV/°C
TEMPERATURE (°C)
TYPE J
TYPE K
TYPE S
-250 0 250 500 750 1000 1250 1500 1750
0
10
20
30
40
50
60
70
SEEBECKCOEFFICIENT-µV/°C
TEMPERATURE (°C)
TYPE J
TYPE K
TYPE S

24. Thermocouple Basics
24
T1
METAL A
METAL B
THERMOELECTRIC
EMF
RMETAL A METAL A
R = TOTAL CIRCUIT RESISTANCE
I = (V1 – V2) / R
V1 T1 V2T2
V1 – V2
METAL B
METAL A METAL A
V1
V1
T1
T1
T2
T2
V2
V2
V
METAL AMETAL A
COPPER COPPER
METAL BMETAL B
T3 T4
V = V1 – V2, IF T3 = T4
A. THERMOELECTRIC VOLTAGE
B. THERMOCOUPLE
C. THERMOCOUPLE MEASUREMENT
D. THERMOCOUPLE MEASUREMENT
I
V1 T1
METAL A
METAL B
EMF
RMETAL A METAL A
R = TOTAL CIRCUIT RESISTANCE
I = (V1 – V2) / R
V1 T1 V2T2
V1 – V2
METAL B
METAL A METAL A
V1
V1
T1
T1
T2
T2
V2
V2
V
METAL A
COPPER COPPER
METAL BMETAL B
T3 T4
V = V1 – V2, IF T3 = T4
A. THERMOELECTRIC VOLTAGE
B. THERMOCOUPLE
C. THERMOCOUPLE MEASUREMENT
D. THERMOCOUPLE MEASUREMENT
I
V1

25. Using a Temperature Sensor for Cold-Junction
Compensations
25
TEMPERATURE
COMPENSATION
CIRCUIT
TEMP
SENSOR
T2V(T2)T1 V(T1)
V(OUT)
V(COMP)
SAME
TEMP
METAL A
METAL B
METAL A
COPPERCOPPER
ISOTHERMAL BLOCK
V(COMP) = f(T2)
V(OUT) = V(T1) – V(T2) + V(COMP)
IF V(COMP) = V(T2) – V(0°C), THEN
V(OUT) = V(T1) – V(0°C)
TEMPERATURE
COMPENSATION
CIRCUIT
TEMP
SENSOR
T2V(T2)T1 V(T1)
V(OUT)
V(COMP)
SAME
TEMP
METAL A
METAL B
METAL A
COPPERCOPPER
ISOTHERMAL BLOCK
V(COMP) = f(T2)
V(OUT) = V(T1) – V(T2) + V(COMP)
IF V(COMP) = V(T2) – V(0°C), THEN
V(OUT) = V(T1) – V(0°C)

26. Thermocouple Amplifiers
AD849x Product Features and Description
 Factory trimmed for Type J and K thermocouples
 Calibrated for high accuracy
Cold Junction Compensation (CJC)
 IC temps of 25°C and 60°C
 Output voltage of 5 mV/°C
 Active pull-down
 Rail-to-Rail output swing
 Wide power supply range +2.7 V to ±15 V
 Low power < 1 mW typical
 Package–space saving MSOP-8, lead-free
 Low cost < $1 in volume
 Can measure negative temperatures in single-supply operation
26
Part Number
Thermocouple
Type
Optimized Temp
Range
Measurement Temp
Range
Initial
Accuracy
AD8494 J 0 to 50°C Full J type range ±1°C and ±3°C
AD8495 K 0 to 50°C Full K type range ±1°C and ±3°C
AD8496 J 25°C to 100°C Full J type range ±1.5°C and ±3°C
AD8497 K 25°C to 100°C Full K type range ±1.5°C and ±3°C

27. Demo Using a Temperature Sensor for Cold-
Junction Compensations–CN0271
Figure 1. K-type thermocouple measurement system with integrated
cold junction compensation (simplified schematic: all connections
not shown)
27
AD8495
OUT
SENSE
REF –VS
+VS
+VS
–VS
INP
INN
0.1µF 10µF
+5V
+2.5V
COLD
JUNCTION
COMPENSATION
THERMO-
COUPLE
1MΩ
100Ω
49.9kΩ
0.01µF
0.01µF
1.0µF100Ω
0.1µF 0.1µF10µF
+5V +2.5V
IN-AMP
+OUT
–OUT
AD8476
10kΩ
10kΩ
10kΩ
10kΩ
100Ω 0.01µF
0.01µF
1.0µF
100Ω SERIAL
INTERFACE
INTERNAL
CLOCK
16-BIT
ADC
GND
REFIN
AD7790
DIGITAL
PGABUF
VDD
VDD
GND
+5VADR441
+5V
+2.5VVIN VOUT
GND
10598-001

28. High Accuracy Applications
Thermocouple Cold-Junction Compensation
Benefits
 High accuracy
 High accuracy, 0.25C, low drift cold junction measurement using
ADT7320/7420
 Fast throughput
 Parallel measurement of hot and cold junction gives fastest throughput
 Flexibility
 Software-based solution
enabling use of multiple
thermocouple types
 Easy implementation
 Fully integrated digital
temp measurement
solution
 Low cost
 No costly multipoint
cold-junction calibration
required
28

29. High Accuracy Applications CJC using ADT7320
29
ADT7320 for cold-
junction temperature
measurement
Thermocouple
isothermal
connector
ADT7320
mounted on
Flex PCB
Σ-Δ ADC

30. Temperature Measurement RTD Sensor
Key application benefits
 3-wire RTD
 2 matched excitation currents
 24-bit ADC resolution
 40 nV RMS at gain = 64
 Ratiometric configuration
 50 Hz and 60 Hz rejection (−75 dB)
30
RL1
RL2
RL3
RTD
GND VDD
AD7793
SERIAL
INTERFACE
AND
CONTROL
LOGIC
INTERNAL
CLOCK
CLK
SIGMADELTA
ADC
IOUT1
MUX
IN-AMP
REFIN(+) REFIN(-)BANDGAP
REFERENCE
GND
SPI SERIAL
INTERFACE
IOVDD
VDD
GND
IOUT2
REFIN
AIN1
RREF
EXCITATION
CURRENTS

31. High Impedance Sensors
Photodiodes
Piezoelectric sensors
 Accelerometers
 Hydrophones
Humidity monitors
pH monitors
Chemical sensors
Smoke detectors
Charge coupled devices
Contact image sensors for imaging
31

32. Photodiode Applications
Optical: light meters, auto focus, flash controls
Medical: CAT scanners (X-ray detection), blood particle analyzers
Automotive: headlight dimmers, twilight detectors
Communications: fiber optic receivers
Industrial: bar code scanners, position sensors, laser printers
32

33. Photodiode Equivalent Circuit
33
PHOTO
CURRENT
IDEAL
DIODE
INCIDENT
LIGHT
RSH(T)
100kΩ -
100GΩ
CJ
Note: RSH halves every 10°C temperature rise

34. Photodiode Modes Of Operation
Photovoltaic
 Zero bias
 No “dark" current
 Linear
 Low noise (Johnson)
 Precision applications
Photoconductive
 Reverse bias
 Has “dark" current
 Nonlinear
 Higher noise (Johnson + shot)
 High speed applications
34
–
+
–VBIAS
–
+

35. Photodiode Specifications
Silicon Detector Part Number SD-020-12-001
Area: 0.2 mm2
Capacitance: 50 pF
Shunt resistance at 25°C: 1000 mW
Maximum linear output current: 40 µA
Response time: 12 ns
Photosensitivity: 0.03 µA/foot candle (fc)
35

36. Short Circuit Current vs. Light Intensity for
Photodiode (Photovoltaic Mode)
36
Environment Illumination (fc) Short Circuit Current
Direct sunlight 1000 30 µA
Overcast day 100 3 µA
Twilight 1 0.03 µA
Full moonlit night 0.1 3000 pA
Clear night/no moon 0.001 30 pA

37. Current-to-Voltage Converter (Simplified)
37
ISC = 30pA
(0.001 fc)
+
_
R = 1000MΩ
VOUT = 30mV
SENSITIVITY: 1mV / pA

38. Preamplifier DC Offset Errors
38
~
VOS
IB
IB
R1
R21000MΩ
+
_
IB doubles every 10°C temperature rise
R1 = 1000 MΩ at 25°C (diode shunt resistance)
R1 halves every 10°C temperature rise
DC NOISE GAIN = 1 + R2
R1
OFFSET
RTO
R3
R3 cancellation resistor not effective

39. 39

40. Photodiode Amplifier Design Choices
40

41. Photodiode Amplifier Design Result
41

42. Complete Photodiode Sensing Application
CN0272
Figure 1. Photodiode preamp system with dark current
compensation (simplified schematic: all connections and
decoupling not shown)
42
AVDD
CF
RF
RF
0.1µF
0.1µF
3.3pF
VBIAS
–5V
+1.8V
+0.9V
22pF
AD8065
SFH 2701
AD9629-20
VIN–
VIN+
VCM
INP
INN
VOCM
+2.5V
+OUT
–OUT
AD8475
1kΩ
2.5kΩ
24.9kΩ
24.9kΩ
2.5kΩ
1kΩ
33Ω
33Ω
+5V
–5V
+5V
–5V
TP3
TP2
ADR441
+5V
+2.5VVIN VOUT
GND
GND
TP1
10599-001

43. Tweet it out! @ADI_News #ADIDC13
Visit the Dual Channel Spectroscopy/Colorimetry
Demo Board in the Exhibition Room
43
Circuit Features
 Three modulated LED drivers
 Two photodiode receive channels
 Programmable gain
Circuit Benefits
 Ease of use
 Self contained solution
 Dual channel 16-bit ADC for data
analysis
Complete Design Files
■ Schematic
■ Bill of Material
■ PADs Layout
■ Gerber Files
■ Assembly Drawing
EVAL-SDP-CB1Z
EVAL-CN0312-SDPZ
This demo board is available for purchase:
www.analog.com/DC13-hardware

44. Sensor Resistances Used in Bridge
Circuits Span a Wide Dynamic Range
44
Strain gages 120Ω, 350 Ω, 3500 Ω
Weigh scale load cells 350 Ω to 3500 Ω
Pressure sensors 350 Ω to 3500 Ω
Relative humidity 100 kΩ to 10 mΩ
Resistance temperature devices (RTDs) 100 Ω, 1000 Ω
Thermistors 100 Ω to 10 mΩ
For more information and demonstration of bridge sensors, attend
the Instrumentation – Sensing 2 – session.

45. Position and Motion Sensors
Linear position: linear variable differential transformers (LVDT)
Hall effect sensors
 Proximity detectors
 Linear output (magnetic field strength)
Rotational position:
 Optical rotational encoders
 Synchros and resolvers
 Inductosyn® sensors (linear and rotational position)
 Motor control applications
Acceleration and tilt: accelerometers
Gyroscopes
45

46. 46
MEMS Sensors are Everywhere
Health and Fitness
Products
Smartphones
Automotive Safety
and Infotainment
Precision Agriculture
Avionics and
Navigation
Fleet Management
Asset
Tracking

47. What you can measure:
47

48. What you can measure:
48
Linear Motion

49. ADI’s Motion Signal Processing ™
Enables… Motion Sensing
49
Fleet management
Alarm systems
Motion control and orientation of
industrial robots
Precision agriculture

50. What you can measure:
50
Tilt

51. 51
ADI’s Motion Signal Processing ™
Enables… Tilt Sensing
Leveling
Horizon detection in cameras

52. What you can measure:
52
Vibration & Shock

53. 53
ADI’s Motion Signal Processing ™
Enables… Shock & Vibration Sensing
Power tool safety:
Shock detection
Contact sports & industrial machinery:
impact detection
White goods:
vibration monitoring Predictive maintenance:
Vibration monitoring

54. What you can measure:
54
Rotation

55. 55
ADI’s Motion Signal Processing ™
Enables… Rotation Sensing
Platform/antenna stabilization:
Industrial, maritime, avionics, communications
Digital camera OIS
Automotive Rollover
Detection

56. Measuring complex motion:
56
Inertial Measurement Unit

57. 57
ADI’s Motion Signal Processing ™
Enables… Complex Motion Sensing
Platform Stabilization
Guidance and trajectory:
Mil/Aero
Detection of Motion in Free Space
Precision agriculture

58. Measuring motion
58

59. ADI’s Inertial MEMS Sensors:
Accelerometers measure
linear motion
Gyroscopes measure
rotation
59

60. ADI MEMS SENSORS:
A brief history…
60

61. MEMS at ADI:
In the beginning…
Concept began in ~1986
Market: airbag sensors

62. A little history…
The first airbags used ball-in-tube sensors.
Concept began in ~1986
Market: airbag sensors

63. A little history…
The first airbags used ball-in-tube sensors.
Concept began in ~1986
Market: airbag sensors

64. MEMS at ADI:
In the beginning…
Concept began in ~1986
Market: airbag sensors
1989
Demonstrated first working MEMS
accelerometer
1991
First product samples
ADXL50: ADI’s First
MEMS Device

65. 65
How Do Accelerometers Work?
Strong
M a s s
Weak
M a s s
No Deceleration
M a s s

66. How Do Accelerometers Work?
constant

67. 67
How Do MEMS Accelerometers Work?
Single axis accelerometer in silicon has the same components
 Left / Right (X-axis)
XLeft RightM a s s
Proof Mass
Suspension
Spring
Suspension
Spring
Motion
(ca. 1992-1995)

68. How Do iMEMS Accelerometers Work?
Single axis accelerometer in silicon has the same components
 Left/right (x-axis)
68
(ca. 1992-1995)

69. How Do iMEMS Accelerometers Work?
All moving parts are suspended above the substrate
 Sacrificial layer removed from below moving parts during fabrication
69
(ca. 1992-1995)

70. 70
How Do MEMS Accelerometers Work?
Measurement of deflection is done with
variable differential capacitor "finger sets"
(ca. 1992-1995)

71. Measuring the Position of the Proof Mass
Suspension
Spring
Suspension
Spring
Suspension
Spring
Suspension
Spring
Finger SetsFinger Sets Finger SetsFinger Sets
Proof
Mass
Suspension
Spring
Suspension
Spring
Suspension
Spring
Suspension
Spring
Suspension
Spring
Suspension
Spring
Suspension
Spring
Suspension
Spring
Finger SetsFinger Sets Finger SetsFinger SetsFinger SetsFinger Sets Finger SetsFinger Sets
Proof
Mass
Proof
Mass
X
Y
 Differential capacitance used to pick off motion of
mass
 C1 and C2 is the capacitance between the mass and a set of
fixed fingers
 Keep monitoring (C1 – C2) to determine if the mass has
moved in the X-axis
C1 C2

72. Simplified Reader Architecture
CMOS
sensor
clocks
sensor
AC
(clock domain)
Gain
demodulator
DC
(baseband)
Gain
convert back
to baseband
amplify amplifyexcite

73. What accelerometers measure:
73

74. Measuring Tilt
A = G sinΦ
Acceleration due to tilt is the projection onto the sensitive axis of the gravity
vector.
Φ
Φ
G
Sensitive axis
G
17mg / ° tilt
near level
m
k

75. High Performance Accelerometers
Industry’s Strongest and Most Complete Portfolio
Low-g
High-g
ADXL103
ADXL203
ADXL78
ADXL213
ADXL278
1
2
2
1
2
Two-Pole Bessel Filter
PWM
Output
±1.7g
±1.7g
±1.7g
ADXL337
3
±3g
±35/50/70g
±35/50/70g
±70/250/500g
ADXL001
1
20-22KHz Bandwidth
ADIS16006
2
±5g
200 μg/√Hz rms
SPI
Temp Sensor
ADIS16003
2
±1.7g
110 μg/√Hz rms
SPI
Temp Sensor
0.1° accuracy
Temperature Calibration
Programmable/Alarms/Filtering
ADIS16209/3/1
2
±90, ±180g
ADIS16227/3
3
±70g
ADIS16204
2
Programmable
Capture Buffers
Peak Sample/Hold
±37/70g
Function
Specific
TILT / INCLINOMETER
Embedded FFT/Storage
Programmable Alarm Bands
MultiMode Operation
VIBRATION
ADXL326
±16g
IMPACT
ADIS16240
3
±19g
Programmable Triggers
Event Capture Buffers
ADXL312
3
AECQ-100
Qualified
±1.5/3/6/12g
Up to 13bit resolution
30μA to 140μA power
3
IMPACT
iMEMs XL
ANALOG
iMEMs XL
DIGITAL
iSensor XL
Digital
g
axes
axes
g
axes
g
ADXL206
2
±5g
+175°C Operation
ADXL212
2
±5g
ADXL343
3
±2/4/8/16g
ADXL344
3
±2/4/8/16g
ADXL345
3
±2/4/8/16g
ADXL346
3
±2/4/8/16g
ADXL362
3
±2/4/8g
12bit resolution @ ±2g
<2uA power consumption
ADXL377
3
±200
g
ADXL350
3
Min/Max
Temp Sensitivity
±1/2/4/8g
Focusing on High Performance with:
• Industry Lowest Power Consumption
• Industry Best Precision Over Lifetime
• Industry Best Temperature Range
• Industry Best Sensor/Signal Processing
• Industry Best Integration
… Performance Under All Conditions

76. Highlight Product:
ADXL362: Industry’s Lowest Power MEMS Accel
By far…
< 2 µA at 100 Hz in Measurement Mode
270 nA in Wake-Up Mode
Also helps save system power
 Enables Autonomous, Continuously Operational Motion-activated Switch
 Enhanced Activity/Inactivity Detection
 Deep FIFO

77. ADI’s Inertial MEMS Sensors:
Accelerometers measure
linear motion
Gyroscopes measure
rotation
77

78. Gyro Building Blocks
What does one need?
x
x
x
x
A Good XL
(We already know how to do that)
+
A gizmo that converts
any rotation to a force
+
A coupling
mechanism that
transfers the force
generated by the
“gizmo” to the
accelerometer

79. Gyro Building Blocks
The Coriolis Effect: Converting rotation
to force since 1835
MASS
ROTATION
OSCILLATION
CORIOLIS
FORCE
What is the Coriolis effect?
In plain English… a moving mass, when rotated, imparts a force to
resist change in direction of motion

80. Gyro Building Blocks
x
x
x
x
A Good XL
(We already know how to do that)
+ +
A coupling
mechanism that
transfers the force
generated by the
“gizmo” to the
accelerometer
Mass with
velocity

81. Gyro Building Blocks
x
x
x
x
Coupling mechanism:
Cut a hole in the
middle of XL and drop
the “moving mass”
inside
Mass with
velocity

82. RESONATOR MOTION
Gyro Principle of Operation
82
ACCELEROMETER TETHER RESONATOR TETHER
ACCELEROMETER FRAME
RESONATOR
CORIOLISACCELERATION
APPLIED ROTATION
ANCHOR

83. Gyro Principle of Operation
83
No Rotation

84. Gyro Principle of Operation
84
Rotation Applied

85. How Do Gyros Work?
Video showing motion of proof mass
85

86. Problems with Single Mass Gyros
Single mass gyros generally cannot differentiate between rotation
(which you want to measure) and vibration at the resonant
frequency
86

87. Gyro Principle of Operation
87
Rotation Applied
-
+
ADXRS series design use two beams (masses) resonating in anti-
phase (180° out of phase)
 Shock and vibration is common mode, so differential operation allows rejection
of many errors

88. Gyro Principle of Operation
88
Vibration Applied
-
+
Cancelled out

89. Photograph of Mechanical Sensor
89

90. Problems With Single Mass Gyros…
…are also problems with dual-mass gyros, just to a
lesser extent.
That wasn’t good enough for us.

91. The Latest

92. High Performance Gyro and IMU
Industry’s Strongest and Most Complete
Portfolio
Rate
Grade
Tactical
Grade
> 10 o/hr
in-run Stability
< 10 o/hr
in-run Stability
ADXRS45X
ADIS16265
ADXRS646
ADXRS642
0.015o/s/g
5mA
6 o/hr
16ppm/oC Sensitivity
ADIS1636X /
405/7
ADIS16305
6, 9,
10
4
ADIS16375
6
ADIS16334
6
ADIS16385
6
12o/hr; 0.13mg Stability
0.013o/s/g
Continuous Bias Estimation
<8cm3
40ppm/oC
ADIS16135/3
6o/hr, Yaw
Quad-Core Designs
Industry Leading Vibration
Immunity
ADXRS62x/
652
Vertical Mount
Package option
25ppm/oC Sensitivity
iMEMs Gyro
ANALOG
iMEMs Gyro
DIGITAL
iSensor Gyro
Digital
IMU
(DoF)-X
0.03o/s/g
ADIS16488
ADIS16448
in development
0.015o/s/g
1000o/sec range
40ppm/oC
8cm3
6 o/hr ; 0.1mg
0.009o/s/g
6 - 10
6 - 10
Up to 1200o/sec
ADIS16136
4 o/hr
0.18 ARW
goals
ADIS-NxGn
ADXRS-NxGn

93. Highlight Product:
ADXRS64x High Performance Gyroscope Series
 Quad differential sensor technology
 Pin and package compatible to ADXRS62x family
 Superb vibration rejection
 Sensitivity to Linear Acceleration as low as
0.015°/s/g
 Vibration Rectification as low as 0.0001°/s/g2
 Various flavors:
 Bias stability as low as 12°/hour
 Rate noise density as low as 0.01°/s/√Hz
 Angular measurement range up to 50,000°/s
 Startup time as fast as 3 msec
 Power consumption down to 3.5 mA
ADXRS64x Gyros Feature
ADI’s Unique Quad Differential
Sensor Design

94. MEMS Microphone
94
Just another accelerometer in disguise

95. Microphone Technology Trends to MEMS
 Performance is unaffected by Pb-
free solder reflow temperature
 Replaces high cost manual sorting
and assembly with automated
assembly
 Higher SNR and superior matching
 Higher mechanical shock
resistance
 Wider operating temperature range
 Consumes less current
 Superior performance part-to-part,
overtemperature, and with vibration
95
MEMS
DIGITAL OUTPUT
MEMS
ANALOG OUTPUT
ECM
JFET

96. ADI Microphone Structure
Diaphragm and back plate electrodes form a capacitor
Sound pressure causes the diaphragm to vibrate and change the
capacitance
Capacitance change is amplified and converted to analog or digital
output
DIAPHRAGM
PERFORATED BACK PLATE
SPRING SUSPENSION
SENSE GAP

97. Normal conversation:
60 dB (or 20 MPa) 
0.55 nm (5.5 A)
Crying baby:
110 dB 
170 nm (1700 A)
How Much Does ADI MEMS Microphone
Diaphragm Move?
97

98. Why Use MEMS Microphones?
Performance Density
Electret mics performance degrades quickly in smaller packages
MEMS mics achieve new level of performance in the same volume
as the smallest electrets!
98
70dB
55dB
Microphone Physical Volume (cubic millimeters)
10mm3 100 200 300 400 500 600 700
MEMS MICROPHONES
ELECTRET-BASED
MICROPHONES
SNR
MEMS MICS SHIFTS THE
SNR-TO-VOLUME SLOPE
UP DRAMATICALLY!

99. Why Use MEMS Microphones?
Less Sensitivity Variation vs. Temperature
ECM vs. ADMP441
99
Change (in dB) from original sensitivity

100. Top vs. Bottom Port: Performance Impact
Bottom Port Provides Superior SNR &
Frequency Response
100
 All top-port microphones (MEMS and ECM) currently on the market have sharp peaks
in their high-frequency response, making them unacceptable for wideband voice
applications
 All top-port microphones have low SNR (55…58 dB)
 There are no top-port microphones with high performance currently on the market
ADI Bottom-Port MEMS Microphone Competitor Top-Port MEMS Microphone

101. Industry’s Most Integrated MEMS Mic
ADMP441 integrates more of the signal chain than any other MEMS Mic!
Typical analog output mics (ADMP404) integrate an output amp
Typical digital output mics (ADMP421) integrate an ADC and provide a single bit
output stream (known as “pulse density modulation” or PDM) – which still requires a
filter and some signal processing
 and PDM codecs focus on mobile devices
ADMP441 provides full I2S output – the most common digital audio interface
ADMP441
ADMP421
ADMP404
Secondary
Amplifier
Serializer
I2S, etc. Digital Signal
Processor or
Microcontroller
Filter

102. ADI MEMS Microphone Portfolio
High Performance MEMS Microphones
ADMP441
Full I2S-Output
Most integrated
microphone
available!
ADMP421
61dB SNR
Pulse Density
Modulated (PDM)
Output
Digital Output
Higher Integration
Package
3.35x2.6x0.88 mm
4.72x3.76x1 mm
4x3x1 mm
Analog Output
Flexibility in Signal Acquisition
ADMP405
62dB SNR
200 Hz to 15 kHz Flat
Frequency Response
ADMP401
100 Hz to 15 kHz Flat
Frequency Response
ADMP521
65dB SNR
Pulse Density
Modulated (PDM)
Output
ADMP404
62dB SNR
100 Hz to 15 kHz Flat
Frequency Response
ADMP504
65dB SNR
100 Hz to 15kHz
Frequency Response
65dB SNR Family
62dB SNR Family

103. Tweet it out! @ADI_News #ADIDC13
What We Covered
Sensors are the source
Sensor signals are typically low-level and difficult
Signal conditioning is key to high performance
Silicon sensors are integrated with signal conditioning
Applications keep demanding higher accuracy
Motion sensors with moving silicon elements are driving
systems in all market areas
103

104. Tweet it out! @ADI_News #ADIDC13
Design Resources Covered in this Session
Design Tools and Resources:
Ask technical questions and exchange ideas online in our
EngineerZone ® Support Community
 Choose a technology area from the homepage:
 ez.analog.com
 Access the Design Conference community here:
 www.analog.com/DC13community
104
Name Description URL
Photodiode Wizard Photodiode/amplifier design tool

105. Tweet it out! @ADI_News #ADIDC13
Selection Table of Products Covered Today
105
Part number Description
AD590/592/TMP17 Two-terminal current-out temperature sensor
AD849x Thermocouple amplifier w/cold junction compensation
ADT7320/7420 0.25C accurate digital temperature sensors
AD7793 24-bit ADC with RTD sensor driver
ADA4638 Photodiode amplifier
ADXL362 2µA high-resolution digital accelerometer
ADXRS64X High performance gyroscope series
ADMP404/504 High performance analog microphones
ADMP441 Complete digital microphone w/ filter

106. Tweet it out! @ADI_News #ADIDC13
Visit the K-Type Thermocouple Measurement
System with Integrated Cold-Junction
Compensation (CN0271) in the Exhibition Room
This is a complete thermocouple
measurement system with cold
junction compensation for Type K.
It includes a 16-bit Ʃ-∆ ADC, cold-
junction amplifier, and low noise
instrumentation amplifier to
provide common-mode rejection
for long lines.
106
Image of demo/board
This demo board is available for purchase:
http://www.analog.com/DC13-hardware

107. Tweet it out! @ADI_News #ADIDC13
Visit the Tilt Measurement Demo in the
Exhibition Room
107
Measure tilt using the ADXL203
dual axis accelerometer
This demo board is available for purchase:
www.analog.com/DC13-hardware
SDP-S BOARDSOFTWARE OUTPUT DISPLAY EVAL-CN0189-SDPZ