Characterization of individual weights in transversal filters and application to CCDs

Time-domain sampling and averaging techniques for direct measurement of individual tap weights of transversal filters are considered. The essential features of the measurement and the corresponding instrumentation requirements are discussed from a general viewpoint; guidelines are determined for the implementation of measurement set-ups by using existing circuits and instruments. An application of the technique to the characterization of split-electrode CCD filters is then considered in detail and criteria for the analysis of experimental data are discussed. It is shown that separate evaluation of different sources of errors in the tap weights is possible. In particular, in the devices experimentally studied, three known error sources were quantitatively analyzed: charge-transfer inefficiency, mask misalignments, and uneven charge repartition. Application of the same techniques is also envisaged for the characterization of other CCD devices such as delay lines and imagers.