A single 1.5-V digital chip for a 106 synapse neural network

A digital-chip architecture for a 10⁶-synapse neural network is proposed. It runs on a 1.5-V dry cell to allow its use in portable equipment. An on-chip DRAM cell array stores synapse weights digitally to provide easy programmability and automatic refreshing. A pitch-matched interconnection and a combinational unit circuit for summing product allow a tight layout. A dynamic data transfer circuit and the 1.5-V operation of the entire chip reduce the power dissipation, but the parallel processing nonetheless provides high speed at the 1.5-V supply. Estimated power dissipation of 75 mW and a processing speed of 1.37 giga connections per second are predicted for the chip. The memory and the processing circuits can be integrated on a 15.4-mm×18.6-mm chip by using a 0.5-μm CMOS design rule. A scaled-down version of the chip that has an 8-kb DRAM cell array was fabricated, and its operation was confirmed