Charge coupled device with meander channel and elongated, straight, parallel gate electrode

Claim 1

A transversal filter, comprising a semiconductor substrate of predetermined conductivity type, said substrate having a surface; a pair of substantially band-shaped channel stops formed on the substrate surface and extending in spaced substantially parallel relation, said channel stops comprising a high impurity concentration layer of the predetermined conductivity type formed on said substrate surface, each of said band-shaped channel stops having a plurality of spaced outwardly projecting portions extending therefrom away from the projecting portions of the other; a charge transfer area bounded by the band-shaped channel stops; a plurality of short channel stops comprising a plurality of spaced inwardly projecting portions extending from each of said band-shaped channel stops, said short channel stops alternately extending from each of the band-shaped channel stops toward the center of the charge transfer area, each of the short channel stops terminating at a predetermined space from the opposing band-shaped channel stop, the short channel stops comprising the high impurity concentration layer of the predetermined conductivity type formed on said substrate surface in an interdigitated pattern with the channel stops; a plurality of cells each comprising a small area between next-adjacent short channel stops of a corresponding one of the band-shaped channel stops, said cells being staggered along said charge coupled device; means for forming an asymmetrical depletion layer in each of said cells in a regular arrangement to determine a transfer direction of the charge; a film of electrically insulative material covering the charge transfer area; a pair of elongated parallel gate electrodes over said insulative film, one of said gate electrodes commonly covering the cells of one of the band-shaped channel stops and the other of said gate electrodes commonly covering the cells of the other of the band-shaped channel stops thereby forming a single directional meander-shaped charge transfer channel in the charge transfer area under said pair of gate electrodes, the charge transfer area forming a charge transfer route having a pair of spaced opposite ends and sides including said outwardly projecting portions; a plurality of signal extracting means each in a corresponding outwardly projecting portion of the band-shaped channel stops, each of the signal extracting means extracting a signal from the corresponding outwardly projecting portion; a plurality of weighting circuits for providing a weighting coefficient to extracted signals, each of the weighting circuits being connected to a corresponding one of the signal extracting means; signal input means at one end of the charge transfer area; signal output means at the opposite end of the charge transfer area; filtered signal output means connected to the weighting circuits; and a summing circuit interposed and interconnected between the weighting circuit and the filtered signal output means.