BUF600 Datasheet, PDF (11/14 Pages) Burr-Brown (TI) – HIGH-SPEED BUFFER AMPLIFIER

Direct Drive
+5V
A_V =
Z_O
Z_O + R_O
1
V_I
4 _BUF 8
Z_O
V_O
150Ω
5
Z_O
Z_O
–5V
+5V
R_OUT = Z_O – R_O
1
V_I
4 _BUF 8
Z_O
V_O
150Ω
5
R_OUT
Z_O
Z_O
–5V
A_V = – 6dB
Double Matched
FIGURE 4. Driving Cables.
DRIVING CABLES
The most obvious way is to connect the cable directly to the
output of the buffer. This results in a gain determined by the
buffer output resistance and the characteristic impedance of
the cable, assuming it is properly terminated.
Double termination of a cable is the cleanest way to drive it,
since reflections are absorbed on both ends of the cable. The
cable source resistor is equal to the characteristic impedance
less the output resistance of the buffer amplifiers. The gain
is –6dB excluding of the cable attenuation.
VIDEO DISTRIBUTION AMPLIFIER
In this broadcast quality circuit, the OPA623 provides a very
high input impedance so that it may be used with a wide
variety of signal sources including video DACs, CCD cam-
eras, video switches or 75Ω cables. The OPA623 provides a
voltage gain of 2.5V/V, while the potentiometer of 200Ω
allows the overall gain to be adjusted to drive the standard
signal levels into the back-terminated 75Ω cables. Back
matching prevents multiple reflections in the event that the
remote end of the cable is not properly terminated.
+5V
470nF
2.2µF
120Ω
1
4 _BUF601 8
68Ω
V_O
5
+5V
470nF 2.2µF
–5V
470nF 2.2µF
120Ω
1
4 _BUF601 8
68Ω
V_O
+5V
5
V_I
150Ω
3
7
6
OPA658
2
+5V
470nF 2.2µF
–5V
470nF 2.2µF
75Ω
4
–5V
200Ω
120Ω
1
4 _BUF601 8
68Ω
V_O
250Ω
100Ω
5
2.2µF
470nF
FIGURE 5. Video Distribution Amplifier.
–5V
11
®
BUF600, 601