Operational limitations of charge transfer devices

Abstract

The incomplete transfer of charge and the existence of random noise lead to the primary operational limitations of charge transfer devices. Owing to the signal dependence of the residual charge, which accumulates as a result of the incomplete transfer, signal detection with static detection levels becomes seriously impaired before the onset of significant signal attenuation or noise degradation. A scheme using dynamic detection levels is found to greatly extend the operational range of CTD's and achieves the minimum possible error rate for detecting uncorrelated charge packet sizes. By contrast, simple coding procedures are found to be ineffective in overcoming signal degradation due to incomplete transfer. Shannon's expression for maximum information transmission capacity is transformed into an expression for maximum information storage capacity. It is found that significantly larger storage capacities are possible with CTD's than have been achieved.