an apparatus , system and method for clamping a video signal input to a coupling capacitor for providing a clamping voltage . a charging current is applied to the capacitor via an amplifier having a first input coupled with the capacitor output and a second input coupled to a reference potential , the amplifier is responsive to the capacitor output signal and the reference potential for providing the charging current to the capacitor . the current has a linearly varying magnitude which is proportional to a difference between the capacitor output and the reference potential .