Welch Allyn PROPAQ CS - Manual (Page 129)

Service Manual Technical overview 125
spo2 block
PULSE OXIMETRY BLOCK DIAGRAM
INTERNAL
PREAMP
AC COUPLED AMP
PEAK DETECTOR
INVERTING AMP
(VAR. GAIN STAGE)
PEAK DETECTOR
COMPARE 1
COMPARE 2
ADC
FILTERS SPLITTERS
SYNCHRONOUS
DETECTOR
CAL
SIGNAL
CPU
LED
DRIVERS
TO
LEDS
CPU
CONTROL
TO SCP
BOARD
IR SIGNAL
RED SIGNAL
DATA/CONTROLS
TO/FROM
CPU
PHOTODIODE
SIGNAL FROM
SENSOR
SWITCH
0696-73