A High Speed Ccd Digitally Programmable Transversal Filter*

A CCD t r a n s v e r s a l f i l t e r w i t h d i g i t a l l y programmable taps i s desc r i b e d . By means of on-chip d i g i t a l c i r c u i t r y the tap weights can he programmed to "0" or " 1 " . M u l t i p l e f i l t e r s can be constructed on a chip together w i t h c i r c u i t r y which scales and sums t h e i r outputs to produce a device w i t h m u l t i l e v e l tap weights. I n order to maximize the .operating speed, the device maintains s i g n a l s i n the charge domain, w i t h v o l t a g e to-charge and charge-to-voltage t r a n s d u c t i o n only at the input and output. Two prototype devices, a 32-stage by 1 b i t and a 16-stage by 4¬ b i t , have been b u i l t and tested a t clock r a t e s i n excess of 10 MHz. The l a t t e r device c o n s i s t s of four 16-stage by 1 b i t f i l t e r s feeding a s t r u c t u r e which scales and sums the charge packets to produce the output.