| 摘要 |
PURPOSE:To obtain a correcting device which can provide gamma correction for a chroma signal and correct phase distortion, by adding a gamma correction circuit to a video amplifying circuit at the pre-stage than a band pass filter. CONSTITUTION:A video signal superimposed with a chrominance signal and a luminance signal is inputted from a terminal 1 and amplified at a transistor (TR) 2 and applied to a gamma correction circuit 3. A series circuit consisting of a diode 4 and a resistor 5 is connected to the collector of the TR2, and when a cathode voltage of the diode 4 starts decreasing, a forward current flows to the diode 4 with a nonlinear increasing characteristic of a minute current region of diode, resulting that a load resistance formed with a collector resistance 7 of the TR2, the diode 4 and a resistor 5 has a nonlinear characteristic, allowing to obtain nonlinear characteristic gain of amplifier. |
