RG = 5.6kΩ
2.8kΩ
G = 10
VO
LA
RG/2
INA128
Ref
RA
2.8kΩ
390kΩ
VG
VG
1/2
OPA2131
NOTE: Due to the INA128’s current-feedback
topology, VG is approximately 0.7V less than
the common-mode input voltage. This DC offset
in this guard potential is satisfactory for many
guarding applications.
1/2
OPA2131
10kΩ
RL
390kΩ
FIGURE 4. ECG Amplifier With Right-Leg Drive.
V+
+5V
10.0V
6
REF102
2
2.5V – ∆V
R1
R2
VO
RG
INA128
4
300Ω
Ref
Pt100
2.5V + ∆V
Cu
Cu
K
VO
RG
INA128
Ref
R3
100Ω = Pt100 at 0°C
FIGURE 5. Bridge Amplifier.
SEEBECK
ISA
COEFFICIENT
–
TYPE
MATERIAL
(µV/°C)
R1, R2
VO
VIN
E
+ Chromel
– Constantan
58.5
66.5kΩ
76.8kΩ
97.6kΩ
102kΩ
RG
INA128
Ref
+
J
+ Iron
– Constantan
50.2
39.4
38.0
R1
C1
0.1µF
1MΩ
K
T
+ Chromel
– Alumel
+ Copper
– Constantan
1
f–3dB
=
2πR1C1
OPA130
= 1.59Hz
FIGURE 7. Thermocouple Amplifier With RTD Cold-
Junction Compensation.
FIGURE 6. AC-Coupled Instrumentation Amplifier.
VIN
R1
–
R1
IO
=
• G
VIN
+
RG
INA128
Ref
IB
A1
IO
Load
A1
IB Error
OPA177
OPA131
OPA602
OPA128
±1.5nA
±50pA
±1pA
±75fA
FIGURE 8. Differential Voltage to Current Converter.
BB [ BURR-BROWN CORPORATION ]
