Partition noise in CCD signal detection

Reset noise in CCD signal charge detection is analyzed experimentally and theoretically. From a reset noise measurement experiment, it has been inferred that reset noise consists of two parts: the sensing capacitance (Cs) dependent part and the effective reset channel length (L) dependent part. Conventional reset noise theory, where the Johnson noise in the reset MOS channel was regarded as the only noise source, agrees with the Csdependent part of measured reset noise. However, it cannot explain the L dependent part. To explain theLdependence, the authors propose "partition noise" caused by carrier partition in the reset MOS channel. Partition noise is analyzed by the unique technique of solving the one-dimensional diffusion equation. As a result, a reset channel capacitance dependent characteristic for partition noise has been derived, which agrees with theLdependent part for measured reset noise. Consequently, in addition to Johnson noise, partition noise is found to be a noise source in CCD signal detection.