California Institute of Technology

Bell Telephone Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

American Telephone and Telegraph, Co.

Calif. Institute of Technology

John J Hopfield

David W Tank

An electronic shift register memory (20) at the molecular level is described. The memory elements are based on a chain of electron transfer molecules (22) and the information is shifted by photoinduced (26) electron transfer reactions. The device of the invention integrates designed electronic molecules onto a VLSI substrate (36), providing an example of a 'molecular electronic device' which may be fabricated.

Molecular shift register based on electron transfer

Apparatus that solves the problem of pattern recognition in a temporal signal that is subject to distortions and time warp. The arrangement embodying the invention comprises a neural network, an input interconnection network, and a plurality of signal modification circuits. A plurality of input leads delivers a preselected characteristic stimulus to associated signal modification units, and in response to an applied stimulus, each signal modification unit develops a plurality of output signals that begins at the time of stimulus application, rises to a peak, and decays thereafter. The mean time delay of each output (time to reach the peak) is different for each of the modification unit output signals. The outputs of the signal modification units are applied to the input interconnection unit wherein connections are made in accordance with the sequences that are to be recognized.

Neural computation by time concentration

A network comprising analog amplifiers with a resistive interconnection matrix that connects each amplifier output to the input of all other amplifiers. The connections embodied in the matrix are achieved with conductances whose values are computed in accordance with the set of decomposition functions for which the solution is sought. In addition to the specified connectivity implemented. Further included is a second matrix that connects externally applied voltages to the amplifier inputs via resistors whose values are also computed in accordance with the set of decomposition functions for which the solution is sought. Still further and in accordance with another aspect of the invention, means are included for varying the amplifier gains from an initial low value to an ultimately high value in the process of arriving at a solution to an applied problem.

Optimization network for the decomposition of signals

Amplifiers, optionally having complementary (positive and negative) outputs, are connected to a matrix of input and output conductors (where the output conductors are each a pair for the case of complementary amplifier outputs). Each connection is implemented with a resistors R.sub.ij =R.sub.ji connecting the output(s) of amplifiers j to the input of amplifiers i, and vice versa, where i and j are the ith and jth amplifiers not necessarily in sequence. The value of each resistor is selected for the nature of the decisional operation intended to satisfy the following circuit equation of motion ##EQU1## where V.sub.j =g(u.sub.j) the output of amplifier j due to an input u.sub.i, C.sub.i is the input capacitance of amplifier i, and R.sub.i is the equivalent of p.sub.i and R.sub.ij according to the equation ##EQU2## and R.sub.ij =R.sub.ji. For the implementation of an associative memory, only positive (or negative) output terminals need be connected by resistors of unit value to input terminals of amplifiers i and j for the amplifier i in which a binary 1 is to be stored. (The amplifier j is one or more of the other amplifiers.) The outputs of the array of amplifiers will produce the entire word stored in response to a few bit-1 input signals I.sub.i to amplifiers so connected by resistors R.sub.ij. For problem solution, the resistance R.sub.ij =R.sub.ji is selected to have a value that, with appropriate signals at all input conductors (perhaps zero) the network will collectively drive to a stable state at the complementary output terminals which provide an output code word that is a very good solution to the problem.

Growing community of inventors

Pasadena, CA, United States of America

John J Hopfield