Datasheet

Coax Cable
V
in
R
in
R
f
V
out
A
2
R
g
R
R
B
1
V
in
V
out
R
f
R
g
R
in
B
2
-
-
-
-
+
+
+
+
d
1 d
T ;
3 6 0 d f
I
V
IN
, V
OUT
(100mV/DIV)
TIME (10 ns/DIV)
V
IN
V
OUT
LMH6628
www.ti.com SNOSA02D –MAY 2002–REVISED MARCH 2013
Figure 29. Delay Circuit Response to 0.5V Pulse
The circuit gain is +1 and the delay is determined by the following equations.
(1)
(2)
where T
d
is the delay of the op amp at A
V
= +1.
The LMH6628 provides a typical delay of 2.8ns at its −3dB point.
FULL DUPLEX DIGITAL OR ANALOG TRANSMISSION
Simultaneous transmission and reception of analog or digital signals over a single coaxial cable or twisted-pair
line can reduce cabling requirements. The LMH6628's wide bandwidth and high common-mode rejection in a
differential amplifier configuration allows full duplex transmission of video, telephone, control and audio signals.
In the circuit shown in Figure 30, one of the LMH6628's amps is used as a "driver" and the other as a difference
"receiver" amplifier. The output impedance of the "driver" is essentially zero. The two R's are chosen to match
the characteristic impedance of the transmission line. The "driver" op amp gain can be selected for unity or
greater.
Receiver amplifier A
2
(B
2
) is connected across R and forms differential amplifier for the signals transmitted by
driver A
2
(B
2
). If R
F
equals R
G
, receiver A
2
(B
1
) will then reject the signals from driver A
1
(B
1
) and pass the
signals from driver B
1
(A
1
).
Figure 30. Full Duplex Transmit and Receive Using the LMH6628
The output of the receiver amplifier will be:
(3)
Copyright © 2002–2013, Texas Instruments Incorporated Submit Documentation Feedback 11
Product Folder Links: LMH6628