| 摘要 |
PURPOSE:To remove reset noise without increasing noise due to a source follower MOSFET by dividing the output of a solid state image pickup device into two parts, delaying the one for a fixed period, and after finding out the difference between the delayed output and the other output, sampling the signal part of the difference. CONSTITUTION:The clock frequency of horizontal scanning and the frequency of a reset pulse are set up in a driving circuit 57 driving the solid state image pickup device 7. An output signal waveform V0 from the device 7 is divided into two parts. The one output is delayed (a half or less of the reset pulse period T of horizontal scanning) by a delay circuit 54, the difference between the delayed output and the undelayed one is found by a subtractor 55 and a difference signal V1 excluding reset noise is outputted. The difference signal V1 is sampled by a sampling pulse phis in a sampling circuit 56, the sampled signal V2 is taken out by an LPF52 and synchronizing signal such as an SYNC is inserted by a signal processing circuit 53, so that a signal excluding the reset noise is outputted. |
