A neuron-MOS neural network using self-learning-compatible synapse circuits

A circuit technology for self-learning neural network hardware has been developed using a high-functionality device called Neuron MOS Transistor (υMOS) as a key circuit element. A υMOS can perform weighted summation of multiple input signals and thresholding all at a single transistor level based on the charge sharing among multiple capacitors. An electronic synapse cell has been constructed with six transistors by merging a floating-gate EEPROM memory cell into a new-concept υMOS differential-source-follower circuitry. The synapse can represent both positive (excitatory) and negative (inhibitory) weights under single V_DD power supply and is free from standby power dissipation. An excellent linearity in the weight updating characteristics of the synapse memory has been also established by employing a simple self-feedback regime in each cell circuitry, thus making it fully compatible to the on-chip self-learning architecture of υMOS neural networks. The basic operation of the synapse cell and a υMOS neural network using the synapse has been experimentally verified using test circuits fabricated by a double-polysilicon CMOS process