Design of a circulating-type analogue--digital convertor using bucket-brigade delay lines

A hardware implementation of a circulating-type analogue--digital convertor using bucket-brigade delay lines (b.b.d.l.) is described. The b.b.d.l. used is a 32-stage commercially available device. This large number of stages is not necessary, and, in practice, a b.b.d.l. with two or three stages would be satisfactory. Such an analogue--digital convertor can be implemented economically, and would be able to convert input signals in the frequency range 0--500 kHz. The principal advantage in using the b.b.d.l. is in the reduction of the number of analogue switches required. Experimental results show that 4--6 bit conversion is readily achieved, although a compensator network to compensate for the b.b.d.l. losses is required.