Four-quadrant CCD analog multiplier

Sequential processing technique improves accuracy when CCD-array signals are multiplied by weighting function to remove offsets. System uses two schemes to cancel undesired output contributions arising from prerequisite biases. First is spontaneous cancellation by multiple "nominally identical" devices; second is sequential cancellation where same devices are used repeatedly to form multiple products. Single device then successively subtracts products, eliminating effects of MOS-array threshold nonuniformities.