Respironics Alice PDx Use and care manual

Alice®PDxTM
Service & Technical Reference Manual

PAGE I1054417, VER. 01
Alice®PDxTM Service & Technical Reference Manual
© 2009 Koninklijke Philips Electronics N.V.

1054417, VER. 01PAGE II
Alice®PDxTM Service & Technical Reference Manual
LIMITED WARRANTY
Respironics, Inc. warrants that the Alice PDx device shall be free from defects of workmanship and materials
and will perform in accordance with the product specifications for a period of two years from the date of sale by
Respironics, Inc. to the customer. If the product fails to perform in accordance with the product specifications,
Respironics, Inc. will pay customary freight charges from Respironics, Inc. to the customer location only. This
warranty does not cover damage caused by accident, misuse, abuse, alteration and other defects not related
to material or workmanship.
Respironics, Inc. disclaims all liability for economic loss, loss of profits, overhead or consequential damages
which may be claimed to arise from any sale or use of this product. Some states do not allow the exclusion or
limitation of incident or consequential damages, so the above limitation or exclusion may not apply to you.
This warranty is given in lieu of all other express warranties. In addition, any implied warranties—including any
warranty of merchantability or fitness for the particular purpose—are limited to one year. Some states do not
allow limitations on how long an implied warranty lasts, so the above limitation may not apply to you. This
warranty gives you specific legal rights, and you may have other rights that vary from state to state.
To exercise your rights under this warranty, contact Respironics, Inc. at:
APPLICABILITY OF WARRANTY
The terms and conditions of this warranty are applicable as between Respironics, Inc. and the customer as to
either a sale of the equipment, or to a transaction whereby Respironics, Inc. sells or conveys such equipment
to a third party for lease to the customer. The limitations and warranty provision herein shall ensure the benefit
of Respironics, Inc. and any manufacturer of the equipment sold by Respironics, Inc.

PAGE III1054417, VER. 01
AlicePDxTM Service & Technical Reference Manual
ALICE PDXINTRODUCTION
OVERVIEW ...............................................................................................................................1
INTENDED USE .........................................................................................................................1
SERVICE NOTICE......................................................................................................................1
SERVICE TRAINING...................................................................................................................1
SERVICE/TECHNICAL SUPPORT STATEMENT..............................................................................1
WARNINGS, CAUTIONS, & NOTES
WARNINGS...............................................................................................................................4
CAUTIONS................................................................................................................................5
SPECIFICATIONS
PHYSICAL SPECIFICATIONS.......................................................................................................7
OPERATING SPECIFICATIONS ....................................................................................................8
ELECTROMAGNETIC EMISSIONS ................................................................................................9
ELECTROMAGNETIC IMMUNITY ................................................................................................10
THEORY OF OPERATION
OVERVIEW .............................................................................................................................13
DETAILED CIRCUIT DESCRIPTIONS ..........................................................................................14
ANALOG PCA........................................................................................................................14
ECG .....................................................................................................................................14
EEG/EOG.............................................................................................................................15
EOG .....................................................................................................................................16
EFFORT BELT ........................................................................................................................16
PRESSURE/SNORE/RESPIRATION SENSOR ..............................................................................17
DIGITAL PCA.........................................................................................................................18
MICROCONTROLLER ...............................................................................................................18
THERMISTOR CIRCUIT.............................................................................................................18
BODY POSITION SENSOR (ACCELEROMETER) .........................................................................19
16-BIT ANALOG TO DIGITAL CONVERTER................................................................................19
ANALOG REFERENCE SUPPLY ................................................................................................19
POWER SUPPLIES ..................................................................................................................19
ACTIMETRY UART (U1).........................................................................................................21
ANALOG VOLTAGE REFERENCE..............................................................................................21
NON-VOLATILE DATA STORAGE .............................................................................................21
ADDITIONAL DATA STORAGE..................................................................................................21
LCD DRIVER .........................................................................................................................22
BATTERY PCA.......................................................................................................................22
BATTERIES ............................................................................................................................22
OVERCURRENT PROTECTION ..................................................................................................22
REVERSE POLARITY PROTECTION...........................................................................................22

1054417, VER. 01PAGE IV
AlicePDxTM Service & Technical Reference Manual
THEORY OF OPERATION (CONT.)
SD CARD ..............................................................................................................................22
INDICATOR LED.....................................................................................................................22
TROUBLESHOOTING
COMMON PROBLEMS .............................................................................................................23
ERROR CODE TABLE .............................................................................................................23
REPAIR AND REPLACEMENT
RP KIT REFERENCE TABLE....................................................................................................30
BENCH CHECKOUT ................................................................................................................31
REPLACEMENT PROCEDURES .................................................................................................32
REPLACING THE BATTERY DOOR & BATTERIES ......................................................................32
REPLACING THE BATTERY ENCLOSURE ..................................................................................33
REPLACING THE BATTERY PCA .............................................................................................34
REPLACING THE POWER BUTTON ...........................................................................................35
REPLACING THE DISPLAY ENCLOSURE ...................................................................................36
REPLACING THE MAIN PCA STACK ........................................................................................39
REPLACING THE DISPLAY HOLDER AND/OR DISPLAY (LCD)....................................................42
REPLACING THE CANNULA PORT............................................................................................44
REPLACING THE CLAMSHELL ASSEMBLY ................................................................................45
CLEANING AND MAINTENANCE
ALICE PDXDEVICE AND HOLSTER .........................................................................................46
CARRYING CASE....................................................................................................................46
LANYARD ..............................................................................................................................46
PERFORMANCE VERIFICATION/POST SERVICE TESTING
PROCEDURE ..........................................................................................................................47
TESTING DATA SHEET
SCHEMATICS

PAGE 11054417, VER. 01
Alice®PDxTM Service & Technical Reference Manual
ALICE PDXINTRODUCTION
OVERVIEW
Alice PDx is a portable, diagnostic recording device. It may be used for obstructive sleep apnea screening as
well as for follow-up and diagnostic assessment. The device may be used in a sleep lab or clinical setting by
trained professionals, and it may be used at home by patients as directed by their health care provider.
The Alice PDx device is capable of recording various physiologic inputs and storing the data locally on the
removable storage card. The device may also be connected directly to a computer running the Sleepware®
software application. Sleepware can display live or pre-recorded data in a resolution consistent with the
computer hardware specifications.
INTENDED USE
The Alice PDx is a multi-function recording device that collects and stores physiological signals. The recorded
data is downloaded, presented graphically on a computer screen, and may be printed for diagnostic review by
clinicians/physicians to aid in the diagnosis of respiratory sleep disorders or other physiological disorders. The
Alice PDx may be used on adults in the home or hospital/institutional environment.
The device does not provide alarms and is not intended for use as an automated apnea or cardiac monitor.
SERVICE NOTICE
The Alice PDx is designed so that qualified Service Technicians can perform repair and testing procedures.
Only qualified personnel should repair this product using authorized parts.
SERVICE TRAINING
Respironics offers service training for the Alice PDx. Training includes complete disassembly of the device,
troubleshooting subassemblies and components, and performance testing. For more information, contact the
Respironics Service department at:
E-mail: [e-mail]
Phone: [phone]
Fax: [phone]
SERVICE/TECHNICAL SUPPORT STATEMENT
For technical assistance, please contact Respironics Customer Satisfaction.
CAUTION
U.S. federal law restricts this device to sale by or on the order of a physician.
U.S.A. and Canada
Phone: [phone]
Fax: [phone]
International
Phone: [phone]
Fax: [phone]

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PAGE 31054417, VER. 01
Alice®PDxTM Service & Technical Reference Manual
WARNINGS, CAUTIONS, & NOTES
Warnings, cautions, and notes are used throughout this manual to identify possible safety hazards, conditions
that may result in equipment or property damage, and important information that must be considered when
performing service and testing procedures on the Alice PDx device. Please read this section carefully before
servicing the Alice PDx.
WARNING
Warnings indicate the possibility of injury to people.
CAUTION
Cautions indicate the possibility of damage to equipment.
NOTE
Notes are used to emphasize important information.

1054417, VER. 01PAGE 4
Alice®PDxTM Service & Technical Reference Manual
WARNINGS
WARNINGS
•Perform Service procedures only in an ESD-protected environment.
•This device is not intended for life support.
•Do not service the Alice PDx device in a Magnetic Resonance Imaging (MRI) environment or
in close proximity to a high emissions source.
•The Alice PDx system and software are not designed to replace the clinical judgement and
analysis of a health care professional.
•Do not plug sensor cables into electrical outlets. Cable contact with electrical outlets presents
a serious shock hazard.
•Make sure the conductive parts of electrodes and associated connectors, including the neutral
electrode, do not contact other conductive parts, including earth.
•Oxygen supports combustion. Oxygen should not be used while smoking or in the presence of
an open flame.
•Do not service the device in the presence of a flammable anaesthetic mixture in combination
with oxygen or air, or in the presence of nitrous oxide.
•When attaching the sensors and cables, be careful to route the cables in a manner that will
reduce the possibility of damage to either the sensors or the device.
•Periodically inspect the sensor cables for damage or signs of wear. Replace if damaged.
•Do not immerse the Alice PDx in any fluids.
•Repairs and adjustments must be performed by Respironics-authorized service personnel
only. Unauthorized service could cause injury, invalidate the warranty, or result in costly
damage.
•Use caution when removing damaged batteries and avoid exposing skin to any battery
leakage.
•Recycle or dispose of batteries in accordance with local regulations. Do not incinerate.
•Use only accessories that have been approved by Respironics.
•Connecting the Alice PDx to a device that is not approved by Respironics with the therapy
and/or SleepLink®communication cables, may result in a shock hazard to patient. Only
devices that are IEC 60601-1 approved may be attached to the Alice PDx.
•Ensure that any computer connected to the Alice PDx complies with the safety standard IEC
60950. Only connect the Alice PDx to an IEC 60950 compliant computer when configuring the
device or when viewing a sleep study in real time, carefully following the respective
instructions. Do not connect the Alice PDx to any other USB compatible device.
•Do not use grease, oils, polishes or other petroleum-based products when servicing or
handling the device.
•Precautionary procedures include methods to prevent buildup of electrostatic discharge (e.g.,
air conditioning, humidification, conductive floor coverings, and non-synthetic clothing),
discharging one’s body to the frame of the equipment or system or to earth or a large metal
object, and bonding oneself by means of a wrist strap to the equipment or system, or to earth.

PAGE 51054417, VER. 01
Alice®PDxTM Service & Technical Reference Manual
CAUTIONS
CAUTIONS
•U.S. federal law restricts this device to sale by or on the order of a physician.
•Use only Respironics or factory-authorized replacement parts and accessories.
•Follow all of the manufacturer’s recommendations and instructions for the Alice PDx and all
equipment used with the device.
•Operation of the Alice PDx device may be adversely affected by:
•Electromagnetic fields exceeding the level of 10 V/m in the test conditions of EN 60601-1-2
•The operation of high frequency (diathermy) equipment
•Defibrillators, or short wave therapy equipment
•Radiation (e.g., x-ray, CT)
•Magnetic fields (e.g., MRI)
•Synthetic fabric from draperies or rugs can also cause interference due to static electricity.
Touching an inanimate object (e.g., wall) before handling the system often prevents static build-
up problems.
•Strong transmitter signals from TV, radio, airport, police, fire, and ambulance stations could be
received and may be misinterpreted as heart and/or breath signals. If you are located less than
one mile from any of these sources, ask Respironics Customer Service to assist you in
determining whether your system will operate properly.
•Do not immerse the Alice PDx device in any fluids.
•Do not place liquids on or near the Alice PDx device. If liquids are spilled on the equipment,
discontinue use until it can be determined that the device can be safely operated.
•Performance of the Alice PDx cannot be assured when connected to therapy devices not
manufactured by Respironics.
•If you use an ExG or EEG Neuroground, do not use the right leg/ground ECG lead.
•Never use cleaning agents or harsh chemicals. Never spray cleaner directly onto the device.
•Make sure all parts are thoroughly dry before using.
•Do not autoclave, gas, or pressure sterilize Alice PDx equipment.

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PAGE 71054417, VER. 01
Alice®PDxTM Service & Technical Reference Manual
SPECIFICATIONS
PHYSICAL SPECIFICATIONS
Size
Dimensions 5” L x 3” W x 2” H (12.7 cm x 7.62 cm x 5.08 cm)
Weight Approximately 8 oz. (230 grams), (weight does not include batteries)
Classifications & Standards Compliance
The Alice PDx device is classified as follows:
•Type of Protection Against Electric Shock: Internally powered equipment.
•Degree of Protection Against Electric Shock: Type BF Applied part
•Degree of protection against harmful ingress of water:
•IPX0 (Ordinary protection against the ingress of liquids)
•Mode of Operation: Continuous operation
•Not suitable for use in the presence of a flammable anaesthetic mixture with air, oxygen, or nitrous oxide
The Alice PDx device is designed to conform to the following standards:
•IEC 60601-1, IEC 60601-1-2,
•EN 60601-1, EN 60601-1-2, UL 60601-1, CSA 22.2 No. 601.1, and AS 3200.1.0.
Power Requirements
Three AA (1.5V) alkaline batteries, 0.43 watts (typ).
Temperature and Storage Information
Temperature Operating: 41 °F to 95 °F (5 °C to 35 °C)
Storage: -4 °F to 140 °F (-20 °C to 60 °C)
Humidity Operating & Storage: 15-95% (non-condensing)
Atmospheric Pressure Operating & Storage: 70-102 kPa

1054417, VER. 01PAGE 8
Alice®PDxTM Service & Technical Reference Manual
OPERATING SPECIFICATIONS
SpO2
Accuracy SpO2(70-100%)(± 1 SD) -
•No Motion:
•Adults: ± 2 digits
•Motion
•Adults: ± 2 digits
•Low Perfusion
•Adults: ± 2 digits
Standard Deviation is a statistical measure: up to 32% of the readings may fall
outside these limits.
Heart Rate
•No Motion (18 - 300 BPM):
•Adults: ± 3 digits
•Motion (40 - 240 BPM):
•Adults: ± 5 digits
•Low Perfusion (40 -240 BPM):
•Adults: ± 3 digits
Disposal
Dispose of the system components in accordance with local regulations.

PAGE 91054417, VER. 01
Alice®PDxTM Service & Technical Reference Manual
ELECTROMAGNETIC EMISSIONS
This device is intended for use in the electromagnetic environment specified below. Use, service, and testing of
the device should be performed in such an environment.
GUIDANCE & MANUFACTURER’SDECLARATION - ELECTROMAGNETIC EMISSIONS
EMISSIONS TEST COMPLIANCE ELECTROMAGNETIC ENVIRONMENT
GUIDANCE
RF emissions
CISPR 11
Group 1
Class B
The device uses RF energy only for its internal
function. Therefore, its RF emissions are very low
and are not likely to cause any interference in
nearby electronic equipment.
RF emissions
CISPR 11
Not applicable for battery
operated devices
The device is suitable for use in all establishments,
including domestic establishments.
Harmonic emissions
IEC 61000-3-2
Not applicable for battery
operated devices
Voltage fluctuations/
flicker emissions
IEC 61000-3-3
Not applicable for battery
operated devices

1054417, VER. 01PAGE 10
Alice®PDxTM Service & Technical Reference Manual
ELECTROMAGNETIC IMMUNITY
This device is intended for use in the electromagnetic environment specified below. Use, service, and testing of
the device should be performed in such an environment.
GUIDANCE & MANUFACTURER’SDECLARATION - ELECTROMAGNETIC IMMUNITY
IMMUNITY TEST IEC 60601-1-2
TEST LEVEL
COMPLIANCE
LEVEL EMC ENVIRONMENT GUIDANCE
Electrical fast
Transient/burst
IEC 61000-4-4
±2 kV for power
supply lines
±1 kV for I/O lines
Not applicable for
battery operated
devices
±1 kV for I/O lines
The device is suitable for use in all
establishments, including domestic
establishments.
Surge
IEC 61000-4-5
±1 kV Differential
Mode
±2 kV common
mode
Not applicable for
battery operated
devices
The device is suitable for use in all
establishments, including domestic
establishments.
Voltage dips,
short
interruptions, and
voltage variations
on power supply
input lines
IEC 61000-4-11
<5% UT (>95% dip
in UT) for 0.5 cycle
40% UT (60% dip
in UT) for 5 cycles
70% UT(30% dip
in UT) for 25 cycles
<5% UT(>95% dip
in UT) for 5 sec
Not applicable for
battery operated
devices
The device is suitable for use in all
establishments, including domestic
establishments.

PAGE 111054417, VER. 01
Alice®PDxTM Service & Technical Reference Manual
Conducted RF
IEC 61000-4-6
Radiated RF
IEC 61000-4-3
3 Vrms
150 kHz to 80 MHz
3 V/m
80 MHz to 2.5 GHz
3 Vrms
3 Vrms
Portable and mobile RF communications
equipment should be used no closer to
any part of the device, including cables,
than the recommended separation
distance calculated from the equation
applicable to the frequency of the
transmitter. Recommended separation
distance:
P= maximum output power rating of the
transmitter in watts (W) according to the
transmitter manufacturer and d = the
recommended separation distance in
meters (m).
Field strengths from fixed RF transmitters,
as determined by an electromagnetic site
survey,ashould be less than the
compliance level in each frequency
range.b
Interference may occur in the vicinity of
equipment marked with the following
symbol:
NOTE 1 At 80 MHz and 800 MHz, the higher frequency range applies.
NOTE 2 These guidelines may not apply in all situations. Electromagnetic propagation is affected by absorption and reflection from
structures, objects, and people.
aField strengths from fixed transmitters, such as base stations for radio (cellular/cordless) telephones and land mobile radios,
amateur radio, AM and FM radio broadcast and TV broadcast cannot be predicted theoretically with accuracy. To assess the
electromagnetic environment due to fixed RF transmitters, an electromagnetic site survey should be considered. If the measured field
strength in the location in which the device is used exceeds the applicable RF compliance level above, the device should be observed
to verify normal operation. If abnormal performance is observed, additional measures may be necessary, such as reorienting or
relocating the device.
bOver the frequency range 150 kHz to 80 MHz, the field strengths should be less than 3 V/m.
GUIDANCE & MANUFACTURER’SDECLARATION - ELECTROMAGNETIC IMMUNITY
IMMUNITY TEST IEC 60601-1-2
TEST LEVEL
COMPLIANCE
LEVEL EMC ENVIRONMENT GUIDANCE
d1.2 P=
d1.2 P=
d2.3 P=
80 MHz to 800 MHz
800 MHz to 2.5 GHz

1054417, VER. 01PAGE 12
Alice®PDxTM Service & Technical Reference Manual
RECOMMENDED SEPARATION DISTANCES BETWEEN PORTABLE & MOBILE RF
COMMUNICATIONS AND THE M SERIES BASE PLATFORM SLEEP THERAPY DEVICES
This device is intended for use in an electromagnetic environment in which radiated RF disturbances are
controlled. Electromagnetic interference may be prevented by maintaining a minimum distance between
portable and mobile RF communications equipment (transmitters) and this device as recommended in the
table below, according to the maximum output power of the communications equipment.
RATED MAXIMUM
POWER OUTPUT OF
TRANSMITTER (W)
SEPARATION DISTANCE ACCORDING TO FREQUENCY OF
TRANSMITTER
(m)
150 kHz to 80 MHz 80 MHz to 800 MHz 800 MHz to 2.5GHz
0.01 0.12 0.12 0.23
0.1 0.38 0.38 0.73
11.21.22.3
10 3.8 3.8 7.3
100 12 12 23
For transmitters rated at a maximum output power not listed above, the recommended separation
distance d in meters (m) can be estimated using the equation applicable to the frequency of the
transmitter, where P is the maximum output power rating of the transmitter in watts (W) according
to the transmitter manufacturer.
Note 1: At 80 MHz and 800 MHz, the separation distance for the higher frequency range applies.
Note 2: These guidelines may not apply in all situations. Electromagnetic propagation is affected
by absorption and reflection from structures, objects, and people.
d1.2 P=
d1.2 P=
d2.3 P=

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THEORY OF OPERATION
OVERVIEW
A block diagram of the Alice PDx system is shown in Figure A.
FIGURE A: SYSTEM DIAGRAM
The system consists of a microcontroller, operating under program control, which collects signal inputs from
the various peripheral signal conditioning circuits and stores that information on a removable data storage
media. The system provides a User Interface (UI), which consists of a Liquid Crystal Display (LCD), an Event
push button and a Power push button. A serial data link port, capable of communicating with external devices
such as a Personal Computer (PC), or, various Respironics CPAP and Ventilator products is provided.
The Alice PDx is housed in a two-piece, hinged plastic housing. A removable cover on the back side of the
housing allows user access for replacement of the three “AA” cells, which provide power for the unit. The same
cover also allows access to the removable data storage card.
All of the electrical circuitry is contained on three PCAs, broken down as follows:
•Analog PCA
•Digital PCA
•Battery PCA
A detailed explanation of the circuitry on each PCA will follow.
Serial Data
Nonin
Pulse Oximeter
Module
I2C UART
EEG
EOG
EMG
ECG
Thermistor
Accelerometer
(Body Position)
Effort Belt
Pressure Sensor
Snore
Pressure Based Flow
Pressure
CPAP
or
Ventilator
CPU
dsPIC333FJ256GP710
Actimetry
Sensor
Finger Probe
Electrodes
Electrodes
Serial Data
Event
On/Off
+3.3VA +3.3VD
+5V
LCD
Real-time Clock
EEPROM
SD Card
PC
Ventilator
CPAP
Battery
3x AA
Alkaline or NIMH
Power
Supplies
Z
XY

1054417, VER. 01PAGE 14
Alice®PDxTM Service & Technical Reference Manual
DETAILED CIRCUIT DESCRIPTIONS
ANALOG PCA
ECG
The ECG subsystem consists of three signal conditioning circuits that receive biopotential signals from
electrodes on the patient’s body and convert them to signals suitable for application to the ADC in the
microcontroller. All three channels provide identical gain and frequency response and differ only in input
connections.
All ECG signal conditioners are designed to the following parameters:
•Input voltage range: +/-4 mVDC
•Input coupling type: DC
•Input impedance: 10 Megohm single-ended, 20 Megohm differential
•Bandwidth: 0.318Hz to 200Hz (-3 dB)
•Output voltage range: 0 to 3VDC
•Quiescent output voltage: 1.5VDC
•Total gain: 375
The three ECG channels are ECG-I, ECG-II and ECG-V. Since each of the three signal conditioners contain
identical circuitry, only ECG-I will be discussed here.
In a normal configuration, electrodes are placed on the patient in the following locations: left arm, right arm, left
leg, right leg and chest. ECG-I measures the potential between the left arm and the right arm. ECG-II
measures the potential between the left leg (+) and the right arm (-). ECG-V measures the potential between
the chest electrode (+) and the average voltage of the left arm, right arm and left leg electrodes. Other ECG
channels (known as “leads”) can be derived by the algebraic addition and subtraction of the various channels
by software running in the microcontroller, or in the host computer.
Signal from the patient electrodes enter the Alice PDx unit at J16-1 (left arm) and J16-3 (right arm) and passes
through R1 and R21, which in conjunction with C7 and C22, form lowpass filters for EMC susceptibility
reduction. A Transient Voltage Suppressor (CR4) and conventional diodes CR1A and CR1B provide ESD
protection. Resistors R18 and R20 bias the left and right arm signals approximately 1.5 VDC to ensure these
signals are within the common mode range acceptable to U9.
Amplifier U9 is a low-drift instrumentation amplifier which amplifies the difference between the left and right arm
signals by a factor of 18.7.
The output of U9 is fed to a four pole lowpass active filter formed by U10A and U10B. This filter has a cutoff
frequency (Fc) of 200 Hz (-3dB) and a gain of 20. This filter was designed to have low phase distortion, to
prevent distortion of the ECG waveform. The filtered signal is buffered by amplifier U10D prior to being sent to
the microcontroller ADC.
Amplifier U10C forms an integrator which is used to remove any DC shift that may occur in the amplifier/filter
chain. The integrator has a Tc of 10 seconds and feeds back into the reference input of instrumentation
amplifier U9. The integrator causes the signal at the output of U10B to be centered about ANALOG_REF, even
NOTE
Refer to Alice PDx Analog Board Schematics sheets 1, 2, and 3,
located in the Schematics section beginning on page 53.

PAGE 151054417, VER. 01
Alice®PDxTM Service & Technical Reference Manual
if a DC shift occurs due to amplifier offsets or a small DC offset occurring in the signal input. The action of the
integrator causes the appearance of a single pole of highpass filtering with a cutoff frequency of 0.318 Hz to
appear in the response of the ECG signal conditioning circuit.
EEG/EOG
The EEG signal conditioners serve to amplify and filter the low-level “brain-wave” signals picked up by
electrodes placed on the scalp of the patient such that they are suitable for application to the microcontroller
ADC. There are a total of 5 EEG amplifiers in the Alice PDx system. They are:
•EEG N1 R1
•EEG N2 R1
•EEG N3 R2
•EEG N4 R2
•EEG R1 R2
All EEG signal conditioners are designed to the following parameters:
•Input voltage range: 1000 µVp-p
•Input coupling type: AC
•Input impedance: 2 Megohm single-ended, 4 Megohm differential
•Bandwidth: 0.08 Hz to 35 Hz (-3 dB)
•Output voltage range: 0 to 3 VDC
•Quiescent output voltage: 1.5 VDC
•Total gain: 3000
Since all five signal conditioners function identically, with the exception of their input connections, the operation
of only one amplifier will be described here.
Signal from the electrodes enters the Alice PDx at J7-1 and J7-2 and pass through EMC/ESD protection
components CR19B, R209, C30, CR18A, C32, R210, C129, C130 and C132. The signal then passes through
a highpass RC filter consisting of C158, R63, C159 and R64. This filter serves to remove any DC offset due to
electrogalvanic action of the electrodes and has a cutoff frequency of 0.08 Hz. The signal is amplified by
instrumentation amplifier U1 with a gain of 150.
The amplified signal then passes to a four-pole active filter composed of amplifiers U2A and U2B. This filter
has a gain of 20, a cutoff frequency of 35 Hz, and is designed to minimize phase distortion of the signal.
The filtered signal next travels to amplifier U2D, where it is buffered prior to being sent to the analog input of
the system microcontroller.
A sample of the filtered signal is sent to an integrator formed by U2C. The output of the integrator feeds the
reference pin of U1 and causes the output of U2B to have a quiescent voltage equal to ANALOG_REF, thus,
removing any DC offset due to amplifier offsets.
NOTE
Refer to Alice PDx Analog Board Schematic sheets 4, 5, and 6,
located in the Schematics section beginning on page 53.