Video signal equalization system

摘要

An equalization system for compensating the attenuation of high-frequency signals in a twisted wire cable. An equalizing circuit comprises a number of operational amplifiers with a variable impedance connected in a feedback path. The variable impedance comprises a varactor diode whose capacitance changes with the magnitude of a reverse bias voltage. The reverse bias voltage is controlled using a digital-to-analog converter and a gain amplifier to increase the gain of the operational amplifiers at high frequencies. A microprocessor selects the appropriate reverse bias voltages depending on the length of the twisted wire cable to be compensated