| 摘要 |
PURPOSE:To reduce the flicker of a luminance level caused by a comparator even when a MUSE system television signal whose S/N is undesirable is inputted to the clamp circuit. CONSTITUTION:A 1st differential amplifier means constituting an input stage converts a potential difference into currents I3, I4 having current difference, the currents are folded back onto an output terminal side to charge/discharge a capacitor C1 connecting to the output terminal by the current difference thereby expanding the dynamic range on the output terminal, and an emitter resistor R21 is connected between emitters of 1st and 2nd transistors(TRs) Q1, Q2 to widely set the input dynamic range, then even when much noise component is superimposed onto a synchronizing signal being a ternarized pulse train whose positive and negative portions are symmetrical, an average level of the synchronizing signal is pursued to a reference DC level V1 stably for a short period of time independently of the effect of the noise component. |
