Non-recursive matched filters using charge-coupled devices

CCD bandpass transversal filters using overlapping aluminum/polysilicon gate technology have been fabricated and tested. The measured out-of-band rejection was more than 50 db and the dynamic range was greater than 80 db with good linearity using single-phase clocking. This CCD filter performance has been extended to include the matched filter concept. Fifty tap CCD filters matched to complex signal and noise spectra have been fabricated and tested. These filters are intended to replace conventional analog filter amplifiers in scanning sensors. Test results confirm the substantial increase in signal-to-noise ratio (SNR) predicted. It was also confirmed that the filters remained matched for a range of scan rates (time-domain scaling) by suitably changing the CCD clock frequency and input pulse width. As noted for the bandpass filter, other parameters compare well with those typical of analog filter performance.