Instrumentation amplifier applications – Rainbow Electronics MAX4198_MAX4199 User Manual
Page 11
Instrumentation Amplifier Applications
For applications that require a complete low-power
instrumentation amplifier, refer to the MAX4194–
MAX4197 data sheet. Some differential to single-ended
voltage amplifier applications that don’t require a high
input impedance can use the MAX4198/MAX4199 for
gains of +1V/V or +10V/V. The MAX4198/MAX4199 can
also be used as an instrumentation amplifier building
block. The circuit of Figure 7 takes advantage of the
10pA (max), 0.1pA (typ) bias current of the MAX406A
to form an instrumentation amplifier similar to the
MAX4194 family, except with lower input bias currents.
The MAX406A's low 1.2µA supply current maintains a
low overall supply current.
MAX4198/MAX4199
Micropower, Single-Supply, Rail-to-Rail
Precision Differential Amplifiers
______________________________________________________________________________________
11
MAX4198
5
FB
6
OUT
V
EE
V
CC
1
3
IN+
V
A
REF
2
IN-
V
OUT
V
OUT
= 2V
A
Figure 4. Precision Gain of Two Amplifiers
MAX4198
FB
IN+
V
CC
OUT
IN-
V
A
V
CC
REF
V
OUT
V
OUT
= -V
A
Figure 5. Single-Supply Inverting Amplifier Biased at V
CC
/ 2
MAX4198
5
2
IN-
3
IN+
5
COM
1
REF
1
4
NC
6
NO
IN
FB
6
OUT
V
EE
LOGIC
IN
V
OUT
0
1
-V
A
+V
A
NOTE: MAX4544 PINOUT FOR 6-PIN SOT23-6
V
CC
V
A
V
OUT
MAX4544
Figure 6. Digitally Controlled Precision Gain of ±1 Amplifier
MAX4198
FB
IN-
V
A
IN+
OUT
REF
A1, A2 = MAX406A
V
OUT
= (1 + 2R
2
/ R
1
) (V
B
- V
A
)
V
OUT
V
B
A2
A1
R
2
R
1
R
2
Figure 7. Ultra-Low Input Bias Current (0.1pA) Instrumentation
Amplifiers with 47µA Supply-Current Consumption