Spectral analysis of reset noise observed in CCD charge-detection circuits

The reset noise observed in detection nodes of charge-coupled devices (CCDs), such as CCD image sensors, is theoretically analyzed. The result of the analysis yields an accurate analytic formula for the noise-power spectral density that is typically measured on these devices. The measurement of the noise-power spectral density can be performed readily on any resettable charge-detection node, and the derived formula, therefore, becomes a useful tool for device characterization and testing. The accuracy of the derived theoretical predictions is verified by making comparisons with the measured noise performance of a typical CCD image sensor. Finally, the usefulness of the results obtained from the analysis is demonstrated by identifying an unwanted noise source in the design of a particular CCD charge-detection circuit. Elimination of the identified noise source can thus result in performance improvement of presently manufactured image sensors, since similar circuits are routinely used for charge detection in these devices