LT1195 Просмотр технического описания (PDF) - Linear Technology

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LT1195

Low Power, High Speed Operational Amplifier

Linear Technology 

LT1195

APPLICATIO S I FOR ATIO

Send Color Video Over Twisted-Pair

With an LT1195 it is possible to send and receive color

composite video signals more than 1000 feet on a low cost

twisted-pair. A bidirectional “video bus” consists of the

LT1195 op amp and the LT1187 video difference amplifier.

A pair of LT1195s at TRANSMIT 1, is used to generate

differential signals to drive the line which is back-termi-

nated in its characteristic impedance. The LT1187

twisted-pair receiver, converts signals from differential to

single-ended. Topology of the LT1187 provides for cable

compensation at the amplifier’s feedback node as shown.

In this case, 1000 feet of twisted-pair is compensated with

1000pF and 50Ω to boost the 3dB bandwidth of the

system from 750kHz to 4MHz. This bandwidth is adequate

to pass a 3.58MHz chrome subcarrier and the 4.5MHz

sound subcarrier. Attenuation in the cable can be compen-

sated by lowering the gain set resistor RG. At TRANSMIT

2, another pair of LT1195s serve the dual function to

provide cable termination via low output impedance and

generate differential signals for TRANSMIT 2. Cable termi-

nation is made up of 15Ω and 33Ω attentuators to reduce

the differential input signal to the LT1187. Maximum input

signal for the LT1187 is 760mVP-P.

1.5MHz Square Wave Input and Unequalized

Response Through 1000 Feet of Twisted-Pair

1.5MHz Square Wave Input and Equalized

Response Through 1000 Feet of Twisted-Pair

1195 A109

Multiburst Pattern Passed Through

1000 Feet of Twisted-Pair

1195 A110

Vector Plot of Standard Color Burst Through

1000 Feet of Twisted-Pair

1195 A108

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1195 A111

1195fa

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