Depletion-capacitance-induced distortion in surface-channel c.c.d. transversal filters

The effects of depletion-capacitance-induced distortion in split-electrode surface-channel c.c.d. transversal filters are analysed. Two standard charge-inputting techniques (the `diode cut off¿¿ and `fill and spill¿¿ schemes) and the two usual tapping methods (voltage and current sensing) are considered. The analysis of each input-output combination is used to predict the performance of a lowpass c.c.d. filter. Ignoring charge partitioning, the diode-cut off scheme, in conjunction with current sensing, provides an overall response which is linear. If charge partitioning is significant, however, a filter employing a fill-and-spill scheme in conjunction with current sensing gives the least distortion.