OPA3680 Datasheet, PDF (13/22 Pages) Burr-Brown (TI) – Triple, Wideband, Voltage-Feedback OPERATIONAL AMPLIFIER With Disable

+5V
V_DIS
2kΩ
+5V
Video1
75Ω
49.9Ω
1/3 ^DIS
OPA3680
402Ω
100Ω
–5V
100Ω
100Ω
Video2
75Ω
49.9Ω
2kΩ
100Ω
+5V
1/3
OPA3680
DIS
–5V
402Ω
+5V
1/3
OPA3680
DIS
75Ω
–5V
249Ω
374Ω
FIGURE 5. Buffered 2-to-1 MUX.
124Ω
V₁
249Ω
124Ω
V₂
249Ω
124Ω
V₃
249Ω
1/3
OPA3680
249Ω
1/3
OPA3680
249Ω
1/3
OPA3680
249Ω
24.9Ω
100pF
24.9Ω
100pF
24.9Ω
100pF
Triple
ADC
FIGURE 6. Triple ADC Driver.
TRIPLE ADC DRIVER
Figure 6 shows the OPA3680 driving a triple ADC. Most
ADC’s are defined for single +5V operation. The OPA3680
can be adapted to single +5V as well using the techniques
described for Figure 2. The signal flowthrough pinout for the
OPA3680 allows a higher signal fidelity through higher
frequencies due to the simplified PC layout requirements.
WIDEBAND INTEGRATOR
The three unity-gain stable, voltage-feedback amplifiers in
the OPA3680 may be used to develop an exceptional inte-
grator function, as shown in Figure 7. This circuit effectively
multiplies the open-loop gain using two of the amplifiers
and uses the 3rd to provide an input impedance buffering
and low output impedance over broad frequencies required
for proper operation. The interstage attenuator (resistive
divider into the last stage non-inverting input) shown in
Figure 6 is critical to maintaining stability. This circuit can
deliver a 90° phase shift over a 5-decade frequency span.
C
V_IN
50Ω
50Ω
1/3
OPA3680
25Ω
R
50Ω
1/3
OPA3680
150Ω
75Ω
1/3
OPA3680
V_OUT
FIGURE 7. Wideband Integrator.
13
®
OPA3680