| 摘要 |
PROBLEM TO BE SOLVED: To prevent a differential amplifier from being latched up even when the DC level of an input video signal is fluctuated. SOLUTION: The circuit is provided with a capacitor 2 receiving an input signal at its one terminal, a reference power supply 5 that decides a clamp voltage, a comparator 4 that detects a level difference between a voltage at the other terminal of the capacitor 2 and a clamp voltage from the reference power supply 5, charge/discharge circuits 6, 7 that charge/discharge the capacitor in response to an output signal from the comparator 4, and a voltage limiter 11 connecting to the other terminal of the capacitor 2. The voltage limiter prevent the comparator from being latched up. |
