Programmable synaptic weights for an aVLSI network of spiking neurons

We describe a spiking neuronal network which allows local synaptic weights to be assigned to individual synapses. In previous implementations of neuronal networks, the biases that control the parameters of a particular synapse are global to all synapses of the same type regardless of the target neuron. In this new implementation, the parameters for a synapse are set by on-chip digital-analog-converter (DAC) circuits, and the DACs are updated before the selected synapses are activated. Results from the fabricated chip show that the local weights are programmable and the DACs settle in the order of microseconds. These on-chip DACs allow the user to program a selected synaptic weight for connections between neurons and they can also be used for mismatch calibration