Measurement of CCD transfer efficiency by use of feedback to increase the effective number of transfers

A technique is reported that permits accurate measurement of transfer efficiency in charge-coupled devices that have low overall transfer loss (/spl les/1 percent). By adding a feedback loop the signal is passed through the CCD many times, thus increasing the measured transfer loss. A detailed analysis is given that predicts the expected improvement in the minimum measurable transfer loss through the application of feedback. These predictions are then compared with experimental results on both three-phase and two-phase charge-coupled devices.