LT1204 LINER [Linear Technology], LT1204 Datasheet - Page 18

• Manufacturer Part Number: LT1204
• Description: 4-Input Video Multiplexer with 75MHz Current Feedback Amplifier
• Manufacturer: LINER [Linear Technology]

LT1204
TYPICAL
4-Input Twisted-Pair Driver
It is possible to send and receive color composite video
signals appreciable distances on a low cost twisted pair.
The cost advantage of this technique is significant. Stan-
dard 75 RG-59/U coaxial cable cost between 25¢ and
50¢ per foot. PVC twisted pair is only pennies per foot.
Differential signal transmission resists noise because the
interference is present as a common mode signal. The
LT1204 can select one of four video cameras for instance,
18
#2 OUTPUT
Multiburst Pattern Passed Through 1000 Feet of Twisted Pair,
A0 PIN 9
OUTPUT
INPUT
LT1204
CABLE
Differential Receiver Switching Waveforms
A
PPLICATI
No Cable Compensation
O
U
S
1204 TA08
1204 TA05
OUTPUT
and drive the video signal on to the twisted pair. The circuit
uses an LT1227 current feedback amplifier connected with
a gain of – 2, and an LT1204 with a gain of 2. The 47
resistors back-terminate the low cost cable in its charac-
teristic impedance to prevent reflections. The receiver for
the differential signal is an LT1193 connected for a gain of
2. Resistors R1, R2 and capacitors C1, C2 are used for
cable compensation for loss through the twisted pair.
Alternately, a pair of LT1204s can be used to perform the
differential to single-ended conversion.
Multiburst Pattern Passed Through 1000 Feet of Twisted Pair,
INPUT
–20
–40
–60
20
0
10k
Differential Receiver Response
V
R
S
L
DIFFERENTIAL MODE RESPONSE
with Cable Compensation
= 15V
= 100
100k
FREQUENCY (Hz)
COMMON MODE RESPONSE
1M
10M
1204 TA06
100M
1204 TA09
OUTPUT