Patent ID: 7050116

Claim:
A video circuit input stage comprising: a coupling capacitor for receiving a video signal; a variable gain amplifier and an analog-to-digital converter, electrically coupled to the coupling capacitor, for sampling the video signal; an analog regulating circuit, enabled upon reception of a reference signal at the beginning of each line synchronization, the analog regulating circuit having a first input electrically coupled to an output of the variable gain amplifier for receiving an output voltage therefrom, a second input for receiving a clamp voltage reference, and an output, electrically coupled to the coupling capacitor, for providing a charging current for charging the coupling capacitor to precisely set an input voltage of the received video signal, voltage of the received video signal, and wherein the analog regulating circuit includes a voltage-current converter for providing a charging current according to a potential difference existing between the first and second inputs; a digital processing unit, electrically coupled to the analog-to-digital converter, for receiving samples generated by the analog-to-digital converter, the digital processing unit controlling the clamp voltage reference provided to the second input of the voltage-current converter; and a differential converter allowing transmission of the video signal on two channels in opposing phase, centered on the common mode potential, and wherein the variable gain amplifier and the analog-to-digital converter comprise differential circuit structure.