OPA2691ID Datasheet, PDF (13/30 Pages) Texas Instruments – Dual Wideband, Current-Feedback OPERATIONAL AMPLIFIER With Disable

+5V
V_DIS
2kΩ
Video 1
75Ω
+5V
Power-supply
decoupling not shown.
1/2 ^DIS
OPA2691
340Ω
340Ω
–5V
402Ω
402Ω
+5V
82.5Ω
75Ω Cable
RG-59
82.5Ω
Video 2
75Ω
2kΩ
1/2
OPA2691
DIS
–5V
FIGURE 4. Two-Channel Video Multiplexer.
+5V
Power-supply
decoupling not shown.
5kΩ
0.1µF
100pF
V_I
51Ω
5kΩ
1/2
OPA2691
32.3Ω
105Ω
150pF
1/2
OPA2691
600Ω
375Ω
20MHz, 2nd-Order Butterworth Low-Pass
125Ω
0.1µF
12
8
4
4V_I
0
–4
–8
–12
0.1
20MHz, 2ND-ORDER BUTTERWORTH
LOW-PASS FREQUENCY RESPONSE
1
10
100
Frequency (MHz)
FIGURE 5. Buffered Single-Supply Active Filter.
HIGH-SPEED ACTIVE FILTERS
Wideband current-feedback op amps make ideal elements
for implementing high-speed active filters where the amplifier
is used as a fixed gain block inside a passive RC circuit
network. Their relatively constant bandwidth versus gain,
provides low interaction between the actual filter poles and
the required gain for the amplifier. Figure 5 shows an ex-
ample single-supply buffered filter application. In this case,
one of the OPA2691 channels is used to setup the DC
operating point and provide impedance isolation from the
signal source into the 2nd-stage filter. That stage is set up to
implement a 20MHz maximally flat Butterworth frequency
response and provide an AC gain of +4.
OPA2691
13
SBOS224D
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