7700 MultiFrame Manual
7700ADA7-EQ Equalizing Analog Video Distribution Amplifier
Page - 6
Revision
1.2
5. CIRCUIT
DESCRIPTION
The input signal enters the board through a BNC with isolated ground so that balanced input processing
may be done to remove any common mode hum that may have been added to the signal and ground
shield. On-board jumpers allow you to configure the input impedance and input coupling (AC/DC).
For video applications, the synchronization pulses are analyzed for position and size information. A clamp
pulse is generated from the sync information and a clamp signal is delivered to a DC restorer circuit that
positions the blanking level to ground. This feature can be enabled with a jumper. The time-constant of the
clamping action may be fast or slow and the DC level may be set with a card edge POT.
An adjustable gain stage feeds the cable equalizer that can adjust the frequency response to match the
attenuation of up to 300m of coaxial cable. Three separate OP-Amps drive the nine output BNC's with 75-
Ohm output impedance.
