| 摘要 |
A charge transfer imager useful for charge summing includes a photosensitive area for producing image charge, a floating diffusion for converting the image charge to a voltage, an output register for transferring the image charge to the floating diffusion, and an output circuit including the floating diffusion for producing an output signal that contains image information as a function of the difference between a predetermined reference level and an image level, both levels characterized by respective relatively constant pedestal regions. The imager is part of an imaging device that includes a clock generator for generating a reset signal of predetermined frequency that resets the voltage level of the floating diffusion, and for generating a transport signal that is applied to the output register for shifting the image charge to the floating diffusion at a multiple of the reset clock frequency. By modifying the symmetry of the transitions of the transport signal waveform that cause shifting of the image charge, an asymmetrical pattern of transition is obtained which accordingly affects charge transfer and widens the pedestal regions of the output signal, making them more suitable for subsequent sampling pulse placement.
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