Influence of the clock waveforms on the performance of split-electrode c.c.d. transversal filters

Experiments show that there is a strong influence of the clock waveform on the performance on c.c.d. split-electrode transversal filters if the splits are defined by means of channel-stop islands, which do not allow any surface-potential equilibration along the gate. The effect is absent when this equilibration is allowed by means of a suitably placed floating diffusion which connects the channels below the two portions of the split electrode. The process is modelled with an effective difference of threshold voltages between the two sections of the electrode controlling the transfer. It is thus possible to predict the dependence of the stopband attenuation of the filter on the slope of the clock pulses.