| 摘要 |
PURPOSE:To suppress satisfactorily the reset noise and the low frequency noise which are produced at the output part of a solid-state image pickup element, by providing a double sampling circuit at the next stage of a color separation circuit in order to control the phase and the duty ratio of a double sampling pulse easily and with high accuracy. CONSTITUTION:The output signal of a solid-state image pickup element 12 is supplied to a color separation circuit 15 and allocated every color picture element signal. Thus each color signal is obtained. These color signals are amplified by preamplifiers 131-134 respectively and then clamped (double-sampled) by double sampling circuits 141-144 for each picture element signal. In such a case, the input signals of circuits 141-144 contain the color picture element signals of the same type and therefore have 1/4 frequency of the output signal of the element 12 respectively. Therefore the frequency of the double sampling pulse is reduced down to 1/4 conventional level. Thus it is possible to control easily and with high accuracy the phase and the duty ratio of the double sampling pulse. In such a way, the low frequency noise is suppressed satisfactorily.
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