Analog Devices EVAL-AD5142ADBZ User Manual page 6

UG-472
Signal Amplifier
The RDAC can be operated as an inverting or noninverting
signal amplifier supporting linear or pseudologarithmic gains.
Table 7 shows the available configurations.
The noninverting amplifier with linear gain is shown in Figure 4,
and the gain is defined in Equation 3.
R
= 1 + WB2
G
R
AW2
where:
R is the code loaded for the R
WB2
R
is the code loaded for the R
AW2
R41
1.7kΩ
V
IN
W2
A2
R43
A2
RDAC2
Figure 4. Linear Noninverting Amplifier
R43 and R42 can be used to set the maximum and minimum
gain limits.
The noninverting amplifier with pseudologarithmic gain is
shown in Figure 5, and the gain is defined in Equation 4.
RDAC2
= +
G 1
−
256 RDAC2
where:
RDAC2 is the code loaded in the RDAC2.
R41
1.7kΩ
V
IN
W2
A2
W2
R43
A2
RDAC2
Figure 5. Pseudologarithmic Noninverting Amplifier
R43 and R42 can be used to set the maximum and minimum
gain limits.
resistance.
WB2
resistance.
AW2
VOUT2
C1
10nF
B2
W2
R42
B2
VOUT2
C1
10nF
B2
R42
B2
The inverting amplifier with linear gain is shown in Figure 6,
and the gain is defined in Equation 5.
Note that the input signal, V
R
G − = WB2
R
AW2
where:
R is the code loaded for the R
(3)
WB2
R is the code loaded for the R
AW2
V
IN
R43 and R42 can be used to set the maximum and minimum
gain limits.
The inverting amplifier with pseudologarithmic gain is shown
in Figure 7, and the gain is defined in Equation 6.
RDAC
= −
G
−
256
where:
RDAC2 is the code loaded in the RDAC2.
(4)
V
IN
Figure 7. Pseudologarithmic Inverting Amplifier
R43 and R42 can be used to set the maximum and minimum
gain limits.
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Evaluation Board User Guide
, must be negative.
IN
resistance.
WB2
resistance.
AW2
R41
1.7kΩ
C1
W2
10nF
A2 B2
W2
R43 R42
A2 B2
RDAC2
Figure 6. Linear Inverting Amplifier
2
RDAC 2
R41
1.7kΩ
C1
W2
10nF
A2 B2
W2
R43
R42
A2 B2
RDAC2
(5)
VOUT2
(6)
VOUT2