Patent US 4,155,076

N charge signals G.sub.N-1 . . . G.sub.0, each of different weight in N CCD channels, represent an N bit Gray code. The charge signal G.sub.N-1 representing the most significant Gray code bit is sensed to produce an output charge signal B.sub.N-1 representing the most significant binary digit. The N-1 remaining charge signals are processed by, in each case, adding a charge signal representing one Gray code bit G.sub.j to a charge signal B.sub.j+1 representing the binary digit of next higher significance, spilling the resultant charge down a CCD channel containing a plurality of potential wells and in response to the sensing of how many, if any, of the potential wells fill with charge, producing an output charge representing the binary digit B.sub.j.