| 摘要 |
A clamping circuit for restoring the DC level of video input signals. The clamping circuit comprises a coupling capacitor, a latch, a logic element, a charge switch, and a constant current source. The latch is coupled to the coupling capacitor to receive a video input signal therethrough and comprises a bias current source for generating first and second output signals in response to the AC-coupled signal and a reference voltage. The logic element receives the first and second output signals, generating a charging control signal to the charge switch. The charge switch, responsive to the charging control signal, is turned on to direct the current of the bias current source to the coupling capacitor, raising the level of the AC-coupled signal. Meanwhile, the constant current source continuously discharges the coupling capacitor slowly.
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