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The authors present a spike-triggered adaptive neuron circuit with input current modulation. Unlike adaptive neuron circuits where adaptation is realised by leakage modulation, the circuit presented in this Letter modulates the input current to membrane capacitor. Therefore, it is possible to reduce extra power consumption originating from increased leakage. Threshold voltage modulation of silicon on insulator (SOI) MOSFET by back gate effect is used to change the amount of injected current for the same input voltage. Through this method, the circuit in this work consumed 25.9% less power than the one modulating leakage.

A novel simple neuron circuit is presented. It can realise both the sigmoidal activation function and its derivative. The neuron can be adjusted to suit a wide range of conditions by altering the threshold and gain factor of the activation function.

A basic optoelectronic circuit of an artificial synaptic connection was fabricated in which analogue weights were varied electrically. Circuit simplicity and low current level operation, necessary for a large scale OEIC, were realised.

A basic optoelectronic circuit of an artificial neuron was realised in which synaptic weights were varied electrically. A primitive content addressable memory was constructed using an optical interconnection. The experimental results showed the feasibility of large-scale networks and a one-chip OEIC.