Datasheet

Evaluation Board User Guide UG-258
Rev. 0 | Page 5 of 16
V
IN
RDAC2
B2A2
R42
W2
B2
W2
V
OUT
OAVOUT
A2
C1
10nF
R41
1.7kΩ
R43
09728-005
In addition, R36 can be used to achieve a pseudologarithmic
attenuation. To do so, adjust the R36 resistor until a desirable
transfer function is found.
Signal Amplifier
RDAC2 can be operated as an inverting or noninverting signal
amplifier supporting linear or pseudologarithmic gains. Table 6
shows the available configurations.
Figure 5. Pseudologarithmic Noninverting Amplifier
Table 6. Amplifier Selection Link Options
Amplifier Gain Link Label
Noninverting Linear A27 LINEAR
A29 NONINVERTING
A30 NONINVERTING
Pseudologarithmic A27 PSEUDOLOG
A29 NONINVERTING
A30 NONINVERTING
Inverting Linear A27 LINEAR
A29 INVERTING
A30 INVERTING
Pseudologarithmic A27 PSEUDOLOG
A29 INVERTING
A30 INVERTING
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.
R38
R
G
WB2
−=
(5)
where R
WB2
is the resistor between the W2 and B2 terminals.
V
IN
RDAC2
B2
R42
W2
B2
W2
V
OUT
OAVOUT
C1
10nF
R41
1.7kΩ
R38
2.7kΩ
09728-006
The noninverting amplifier with linear gain is shown in Figure 4,
and the gain is defined in Equation 3.
Figure 6. Linear Inverting Amplifier
R38
R
G
WB2
1+=
(3)
The inverting amplifier with pseudologarithmic gain is shown
in Figure 7, and the gain is defined in Equation 6.
2
2
AW
WB
R
R
G −=
(6)
where R
WB2
is the resistor between the W2 and B2 terminals.
V
IN
RDAC2
B2
R42
W2
B2
W2
V
OUT
OAVOUTC1
10nF
R41
1.7kΩ
R38
2.7kΩ
09728-004
where:
R
WB2
is the resistor between the W2 and B2 terminals.
R
AW 2
is the resistor between the A2 and W2 terminals.
V
IN
RDAC2
B2A2
R42
W2
B2
W2
V
OUT
OAVOUT
A2
C1
10nF
R41
1.7kΩ
R43
09728-007
Figure 4. Linear Noninverting Amplifier
The noninverting amplifier with pseudologarithmic gain is
shown in Figure 5, and the gain is defined in Equation 4.
2
2
1
AW
WB
R
R
G += (4)
Figure 7. Pseudologarithmic Inverting Amplifier
R43 and R42 can be used to set the maximum and minimum
gain limits.
where:
R
WB2
is the resistor between the W2 and B2 terminals.
R
AW 2
is the resistor between the A2 and W2 terminals.