LSI NEURAL CHIP OF PULSE-OUTPUT NETWORK WITH PROGRAMMABLE SYNAPSE

We have fabricated a microchip of a neural circuit with pulse represen tation. The neuron output is a voltage pulse train. The synapse is a c onstant current source whose output is proportional to the duty ratio of neuron output. Membrane potential is charged by collection of synap tic currents through a RC circuit, providing an analog operation simil ar to the biological neural system. We use a 4-bit SRAM as the memory for synaptic weights. The expected I/O characteristics of the neurons and the synapse were measured experimentally. We have also demonstrate d the capability of network operation with the use of synaptic weights , for solving the A/D conversion problem.