Abstract: A single loop analog-to-digital conversion and video clamping circuit includes a low-pass filter and analog amplifier that present the incoming analog video signal to an analog-to-digital converter and to the input of a limit detector and protection circuit. The output of the analog-to-digital converter is sampled an integer multiple of four times during the black interval, with the results being summed and averaged. The resulting value is then scaled and limited, and compared to the desired level for a representation of black. Any resulting error quantity is converted from digital back to, analog and modified if necessary by the output of the limit detector and protection circuit. The signal that results from that modification is low-pass filtered and converted to a current by a transconductance amplifier. The resulting feedback current is then applied to a capacitor in the input circuitry, thereby clamping the input and resulting digital output of the overall circuit to the desired level.