| 摘要 |
PURPOSE:To simplify circuit design wherein the influence of a clock noise is small and reduce a noise due to feedback resistance by providing the open loop gain of a preamplifier with special frequency characteristics. CONSTITUTION:The preamplifier 9 is provided with low-pass characteristics which have the 1st cutoff frequency f1 in a video band as closed loop frequency characteristics. Further, the 2nd cutoff frequency f2 determined by the electrostatic capacity at the input terminal of the preamplifier 9 and the input impedance Rin of the preamplifier 9 is present in the video band, and the cutoff frequency f3 of a feedback loop is also present in the vedio band. For the purpose, only the high frequency range to the cutoff frequency f- is only compensated behind the preamplifier 9.
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