| 摘要 |
PURPOSE:To reduce the number of pins providing a capacitor for clamp to be one by forming a peak clamp circuit to be a feedback type. CONSTITUTION:A video signal is supplied from an input terminal 1 to a differential amplifier 2 composed of transistors 28 and 29 and in a comparator circuit 4, the output signal of the differential amplifier 2 is compared with a reference voltage 3 for clamp. In a clamp capacitor 7, the output current of the comparator circuit 4 is converted to a voltage and held. In an inverted amplifier 8, the voltage held in the clamp capacitor 7 is inverted and the output voltage of the inverted amplifier 8 is supplied to the transistor 29 constituting the differential amplifier 2. Then, a clamp output is taken out from the output of the differential amplifier 2. Thus, the number of IC pin terminals for connecting the clamp capacitor 7 can be reduced to be one and even when using a power source which power supply voltage is low and stability is lacked, a feedback type peak clamp circuit, which is not affected by the fluctuation of the power supply voltage, can be obtained with a sufficiently wide dynamic range. |
