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Preliminary footprints
2017-03-24 20:20:13 -04:00
EESchema Schematic File Version 2
LIBS:power
LIBS:device
LIBS:transistors
LIBS:conn
LIBS:linear
LIBS:regul
LIBS:74xx
LIBS:cmos4000
LIBS:adc-dac
LIBS:memory
LIBS:xilinx
LIBS:microcontrollers
LIBS:dsp
LIBS:microchip
LIBS:analog_switches
LIBS:motorola
LIBS:texas
LIBS:intel
LIBS:audio
LIBS:interface
LIBS:digital-audio
LIBS:philips
LIBS:display
LIBS:cypress
LIBS:siliconi
LIBS:opto
LIBS:atmel
LIBS:contrib
LIBS:valves
LIBS:nocko
LIBS:bmi-8ch-cache
EELAYER 25 0
EELAYER END
$Descr USLetter 11000 8500
encoding utf-8
Sheet 5 5
Title "Input Channel 6 & 7"
Date "2017-03-23"
Rev "AA"
Comp "Monadnock Systems"
Comment1 ""
Comment2 ""
Comment3 ""
Comment4 ""
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Text Notes 1950 1000 0 60 ~ 0
Optional AC Coupling\n3dB down @ 0.4Hz
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Text Notes 750 5450 0 87 ~ 0
Notes:\nDesigned for 0-5V Output\nOutput can swing from AGND to VBATT (5.125-12V) in some failure modes.\nMay damage ADC if input range is <= VBATT\n\nR204, R213: 0.1%\nR208, R209: 1%\nR202, R205, R206 & R203, R207: Metal Foil / Thin Film (Resistor packs preferred)\nALL C: 5%, 16V
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Text Notes 5300 2450 0 60 ~ 0
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When DC coupled, sensor failure grounds output.
Text Notes 2750 2350 0 39 ~ 0
CMRR: >95dB\nInput Voltage Noise Density: <28nV/√Hz\nOutput Voltage Noise Density: <330nV/√Hz\nVoltage Noise (0.1-10Hz): < 0.8μV p-p\n
Text Notes 7150 2400 0 39 ~ 0
Offset: <125uV\nOffset Drift: <1.3uv/°C\nVoltage Noise Density: 12nV/√Hz\nVoltage Noise (0.1-10Hz): 0.2μV p-p
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Antialias Filter
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Text Notes 6950 5250 0 60 ~ 0
Assumptions:\n - (Initial) DAQ is MCC USB-1208FS (available at BMI)\n 11-bit, max 6250 S/sec for each channel; sequential\n - Target Bandwidth: 195Hz\n - Sampling Rate 6240 S/s\n - Sensor resistance ~2MΩ\n - Respiration motion changes sensor resistance by < -+10%
Text Notes 7000 6400 0 60 ~ 0
Analysis Notes:\n\n 1. Steep digital filter 0.4-175Hz\n - Respiration typically 0.25-0.33Hz\n - Narrower useful bandwidth likely, modeling needed.\n\n 2. Correct for temporal offset of sample due to sequential sampling.\n\n 3. 2x decimation for 13-bit (ENOB) and noise reduction
Text Notes 750 7750 0 60 ~ 0
Open Questions:\n\n1. Trimming the bridge.\n - Only makes sense w/ DC coupling\n - Bad tempco\n - Bad UX\n - Needed for significant gain\n\n2. AC vs DC Coupling; both have advantages: AC is easier\n\n3. Reducing R202,R203,R206,R207 to decrease Johnson noise: Probably useless.\n - Changing R202,R206 may break INAMP CMRR\n\n4. Use chopper amps in signal path: Probably bad\n - Lower total noise for *extremely* small bandwidths (<5Hz?)\n - Lower offset (if DC coupled)\n\n5. Driven shields for output: Probably useless\n - Reduce error due to leakage current\n - No analysis done to determine if this is significant\n - Current DAQ isn't likely to benefit
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Text Notes 1950 2850 0 60 ~ 0
Optional AC Coupling\n3dB down @ 0.4Hz
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F 3 "" H 6000 3450 50 0001 C CNN
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F 3 "" H 5600 3450 50 0001 C CNN
1 5600 3450
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F 3 "" H 6250 3750 50 0001 C CNN
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1 0 0 -1
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F 3 "" H 6900 3300 50 0000 C CNN
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F 3 "" H 6900 3800 50 0001 C CNN
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$EndComp
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1 0 0 -1
$EndComp
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G=50
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F 3 "" H 3250 3150 50 0000 C CNN
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$EndComp
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Wire Wire Line
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Connection ~ 1400 3350
Wire Wire Line
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Wire Wire Line
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Connection ~ 1400 2900
Wire Wire Line
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Connection ~ 1600 2900
Wire Wire Line
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Wire Wire Line
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Connection ~ 1600 3800
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Wire Wire Line
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Wire Wire Line
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Wire Wire Line
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Wire Wire Line
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Wire Wire Line
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Wire Wire Line
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Wire Wire Line
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Wire Wire Line
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Wire Wire Line
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Wire Wire Line
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Wire Wire Line
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Connection ~ 6250 3450
Wire Wire Line
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Wire Wire Line
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Connection ~ 5800 3450
Wire Wire Line
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Connection ~ 7600 3550
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Wire Notes Line
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Wire Notes Line
5250 4300 5250 2850
Wire Wire Line
7600 4050 6500 4050
Wire Wire Line
2350 3100 2750 3100
Wire Wire Line
2350 3100 2350 3250
Connection ~ 2500 3100
Wire Wire Line
2350 3650 2350 3800
Wire Wire Line
2500 3400 2500 3500
Wire Wire Line
2400 3450 2500 3450
Connection ~ 2500 3450
Wire Wire Line
1900 3650 2050 3650
Wire Wire Line
2350 3800 2750 3800
Connection ~ 2500 3800
Wire Notes Line
2050 3950 2700 3950
Wire Notes Line
2700 3950 2700 2950
Wire Notes Line
2050 2950 2050 3950
Wire Notes Line
8350 4300 5250 4300
Wire Wire Line
3600 3750 3350 3750
Wire Wire Line
2750 3100 2950 3250
Wire Wire Line
2750 3800 2950 3650
Wire Wire Line
3650 3450 5450 3450
Wire Wire Line
2950 3350 2850 3350
Wire Wire Line
2950 3550 2850 3550
Connection ~ 1750 3350
Wire Wire Line
1750 3350 1900 3350
Text Notes 1950 2900 0 39 ~ 0
When DC coupled, sensor failure grounds output.
Text Notes 2750 4200 0 39 ~ 0
CMRR: >95dB\nInput Voltage Noise Density: <28nV/√Hz\nOutput Voltage Noise Density: <330nV/√Hz\nVoltage Noise (0.1-10Hz): < 0.8μV p-p\n
Text Notes 7150 4250 0 39 ~ 0
Offset: <125uV\nOffset Drift: <1.3uv/°C\nVoltage Noise Density: 12nV/√Hz\nVoltage Noise (0.1-10Hz): 0.2μV p-p
Text Notes 7650 2950 0 60 ~ 0
Antialias Filter
$Comp
L CONN_01X02 J504
U 1 1 58D6DA45
P 9200 3600
F 0 "J504" H 9200 3750 50 0000 C CNN
F 1 "Channel 1" V 9300 3600 50 0000 C CNN
F 2 "" H 9200 3600 50 0001 C CNN
F 3 "" H 9200 3600 50 0001 C CNN
1 9200 3600
1 0 0 1
$EndComp
$Comp
L GNDA #PWR076
U 1 1 58D6DA46
P 9000 3650
F 0 "#PWR076" H 9000 3400 50 0001 C CNN
F 1 "GNDA" H 9000 3500 50 0000 C CNN
F 2 "" H 9000 3650 50 0001 C CNN
F 3 "" H 9000 3650 50 0001 C CNN
1 9000 3650
1 0 0 -1
$EndComp
Text Notes 3500 5950 0 60 ~ 0
Problems:\n\n - AD8622 isn't RRIO; will saturate at (V+)-1.2V.\n Near the end of battery life; this could be less that 5V.
$EndSCHEMATC