INA128

R

G

V

O

C

1

0.1µF

OPA130

Ref

R

1

1M

Ω

f

1

2

πR

= 1.59Hz

V

IN

+

–

FIGURE 4. ECG Amplifier With Right-Leg Drive.

FIGURE 8. Differential Voltage to Current Converter.

OPA177

±1.5nA

OPA131

±50pA

OPA602

±1pA

OPA128

±75fA

SEEBECK

ISA

COEFFICIENT

TYPE

MATERIAL

(

E

+ Chromel

58.5

66.5k

Ω

– Constantan

J

+ Iron

50.2

76.8k

Ω

– Constantan

K

+ Chromel

39.4

97.6k

Ω

– Alumel

T

+ Copper

38.0

102k

Ω

– Constantan

FIGURE 7. Thermocouple Amplifier With RTD Cold-

Junction Compensation.

FIGURE 5. Bridge Amplifier.

FIGURE 6. AC-Coupled Instrumentation Amplifier.

REF102

R

2

R

3

Pt100

Cu

Cu

V+

K

6

10.0V

4

2

INA128

V

O

Ref

100

Ω = Pt100 at 0°C

R

G

INA128

R

G

I

B

R

1

V

IN

–

+

A

1

I

O

Load

I

• G

V

IN

R

1

Ref

INA128

R

R

V

O

LA

RL

RA

10k

Ω

Ref

NOTE: Due to the INA128’s current-feedback

topology, V

the common-mode input voltage. This DC offset

in this guard potential is satisfactory for many

guarding applications.

G = 10

2.8k

Ω

V

G

V

G

2.8k

Ω

1/2

OPA2131

390k

Ω

390k

Ω

1/2

OPA2131

300

Ω

+5V

2.5V –

∆V

2.5V +

∆V

R

G

INA128

V

O

Ref