Implementing delay insensitive oscillatory neural networks using CMOS and emerging technology

One major challenge in efficiently implementing neuromorphic networks is the need for a large number of variable synaptic connections. Networks that use emerging resistive memories as synapses have been proposed to tackle this problem, but interfacing with these devices is still inefficient in deeply-scaled CMOS. Oscillatory Neural Networks (ONNs) use a different paradigm than most analog hardware implementations, and may be able to interface more efficiently with RRAM neurons. Previous work on ONNs, however, has not considered the effects of actual hardware implementation realities, such as delay in the network. In this work, the first reported IC implementation of an oscillatory neural network is designed and fabricated. Modifications are made to the ONN architecture based on theoretical analysis to allow for proper operation in real-world conditions. One modification is changing the PLL-type, giving the system a different dynamic trajectory which is robust to global delays. Additionally, circuitry is added to control the transport delay of the neuron output signals. A chip with the modified ONN architecture is designed and tested in 28 nm CMOS and estimated power and area figures are reported.