| 摘要 |
PURPOSE:To effectively reduce the generation of color phase noise due to noise caused at a sample/hold circuit by providing a noise reduction circuit comprising an HPF, a limiter and a synthesizer or the like between an LPF and a variable phase shifter. CONSTITUTION:A noise reduction circuit 27 is provided between a 2nd-order phase shifter (variable phase shifter) 12 via an LPF 18 and a coefficient multiplier 19 and an output of a sample/hold circuit 17 is fed to an HPF 23 and a synthesizer 25 via an LPF 18. Then the output of an HPF 23 is fed to the synthesizer 25 via a limiter 24 and an on/off switch 26 and an output of the limiter 24 is subtracted from the output of the LPF 18. Since the noise generated in the circuit 17 is reduced, the generation of color phase noise due to the noise generated in the circuit 17 is reduced effectively. That is, even if noise superimposed on the horizontal synchronizing signal of the sampling pulse resides, it is reduced via the circuit 27 and the color phase noise included in the color video signal obtained from the phase device 12 is reduced.
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