Analog Devices EVAL-AD5141DBZ User Manual page 6

UG-473
Signal Amplifier
The RDAC can be operated as an inverting or noninverting
signal amplifier supporting linear or pseudologarithmic gains.
Table 10 and Table 11 show the available configurations.
The noninverting amplifier with linear gain is shown in Figure 4,
and the gain is defined in Equation 3.
R
WB
= 1 +
G
R
AW
where:
R is the code loaded for the R
WB
R is the code loaded for the R
AW
R41
1.7kΩ
V
IN
W2
A2
R43
A
RDAC
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.
RDAC
= +
G 1
−
256 RDAC
where:
RDAC is the code loaded in the RDAC.
R41
1.7kΩ
V
IN
W2
A2
R43
A
RDAC
Figure 5. Pseudologarithmic Noninverting Amplifier
R43 and R42 can be used to set the maximum and minimum
gain limits.
The inverting amplifier with linear gain is shown in Figure 6,
and the gain is defined in Equation 5.
resistance.
WB
resistance.
AW
VOUT2
C1
10nF
B2
W
R42
B
VOUT2
C1
10nF
B2
W
R42
B
Note that the input signal, V
R
WB
= −
G
R
AW
where:
R is the code loaded for the R
WB
R is the code loaded for the R
AW
(3)
V
IN
R43 and R42 can be used to set the maximum and minimum
gain limits.
Table 10. Amplifier Selection Daughter Board Link Options
Link Options
A6 A
A7 A
A8 A
A1 OUT
The inverting amplifier with pseudologarithmic gain is shown
(4) in Figure 7, and the gain is defined in Equation 6.
RDAC
= −
G
256
where:
RDAC is the code loaded in the RDAC.
V
IN
Figure 7. Pseudologarithmic Inverting Amplifier
R43 and R42 can be used to set the maximum and minimum
gain limits.
Rev. 0 | Page 6 of 20
Evaluation Board User Guide
, must be negative.
IN
resistance.
WB
resistance.
AW
R41
1.7kΩ
C1
W2
10nF
A2 B2
W
R43
R42
A B
RDAC
Figure 6. Linear Inverting Amplifier
Description
Connects Terminal A to A2
Connects Terminal W to W2
Connects Terminal B to B2
Open short circuit for the
−
RDAC
R41
1.7kΩ
C1
W2
10nF
A2 B2
W
R43 R42
A B
RDAC
(5)
VOUT2
AD8618
(6)
VOUT2