Datasheet
15
LT1995
1995fb
APPLICATIO S I FOR ATIO
WUUU
AC-Coupling Methods for Single Supply Operation
The LT1995 can be used in many single-supply applications
using AC-coupling without additional biasing circuitry.
AC-coupling the LT1995 in a difference amplifier configu-
ration (as in Figure 1) is a simple matter of adding coupling
capacitors to each input and the output as shown in the
example of Figure 5. The input voltage V
BIAS
applied to the
REF pin establishes the quiescent voltage on the input and
output pins. The V
BIAS
signal should have a low source
impedance to avoid degrading the CMRR (0.5Ω for
1dB CMRR change typically).
M4
M2
M1
P1
P2
P4
8
9
10
1
2
3
V
OUT
V
IN
*
–V
+V
6
4
5
7
LT1995
A = 0.875
REF
M4
M2
M1
P1
P2
P4
8
9
10
1
2
3
V
OUT
V
IN
*
–V
+V
6
4
5
7
LT1995
A = 0.833
REF
M4
M2
M1
P1
P2
P4
8
9
10
1
2
3
V
OUT
V
IN
*
–V
+V
6
4
5
7
LT1995
A = 0.857
REF
M4
M2
M1
P1
P2
P4
8
9
10
1
2
3
V
OUT
V
IN
*
–V
+V
6
4
5
7
LT1995
A = 0.800
REF
M4
M2
M1
P1
P2
P4
8
9
10
1
2
3
V
OUT
V
IN
*
–V
+V
6
4
5
7
LT1995
A = 0.714
REF
M4
M2
M1
P1
P2
P4
8
9
10
1
2
3
V
OUT
V
IN
*
–V
+V
6
4
5
7
LT1995
A = 0.750
REF
M4
M2
M1
P1
P2
P4
8
9
10
1
2
3
V
OUT
V
IN
*
–V
+V
6
4
5
7
LT1995
*CONFIGURE M INPUTS FOR DESIRED G PARAMETER; REFER TO FIGURE 2 FOR CONNECTIONS
A = 0.667
REF
M4
M2
M1
P1
P2
P4
8
9
10
1
2
3
V
OUT
V
IN
*
–V
+V
6
4
5
1995 F03
7
LT1995
A = 0.571
REF
M4
M2
M1
P1
P2
P4
8
9
10
1
2
3
V
OUT
V
IN
*
–V
+V
6
4
5
7
LT1995
A = 0.625
REF
Figure 3. Noninverting Amplifier Input Attenuation Configurations (A > 0.5)
1
1
2
4
5
6
8
1995 F04
3
7
73
GAIN COMBINATION
NONINVERTING GAIN
Figure 4. Unique Noninverting Gain Configurations