Rejection characteristics in a video-signal processor using CCD comb filters

This paper describes charge-coupled device (CCD) combfilter rejection characteristics in the video bandwidth. Notch-frequency shifts and rejection-ratio decreases are caused by the incomplete charge transfer in the CCD channel and also by timing error in the charge sampling, which shorten the effective delay time from the ideal 1 period. In the 1H comb filters, 30-dB rejections are achieved within the 4.5-MHz bandwidth for less than 2 × 10^-5per transfer inefficiency. The timing error in the input section can be compensated for by adjusting the input-gate biasing voltage. The analyses are extended to the 2 comb filter constructed with three identical CCD\´s. The 1.2 × 10^-4inefficiency, which is six times as large compared with that in the 1 filter, is allowable to maintain the 30-dB ratio. The rejection is shown to be constant when the product of the inefficiencies in the series-connected CCD\´s is constant. The experimentally obtained results suggest the analyses are reasonable.