SURFACE CHARGE SIGNAL CORRELATOR

Electrical charges proportional to a sampled value of an analog signal are transferred between surface-adjacent portions of an information channel in a semiconductor substrate. The direction of charge transfer is responsive to control voltages applied to electrodes insulatingly overlying the substrate. A plurality of such information channels connected electrically in parallel to a source of analog signal energy and to output means sensitive to the direction of charge transfer constitute a correlator circuit when additionally some of the control voltages correspond to the bits of a digital reference word with which the analog signal is to be correlated. A portion of electric charge proportional to a sample of the analog signal is gated into each information channel synchronously with each clock pulse as each sequential bit of the digital reference word is applied to control electrodes. Accordingly, the magnitude of signal charge present at a first portion of the information channels is proportional to the correlation of the analog signal with the reference word and the magnitude of signal charge present at a second portion of the information channels is proportional to the correlation of the analog signal with the complement of the reference word.