Neuronova Neuromorphic Chip Overview
This section provides a high-level description of the Neuronova neuromorphic chip architecture. The goal is to give users enough context to understand how networks are mapped to hardware, without going into circuit-level details.
Layer Topology
The chip implements a fixed hierarchical topology:
Filter Bank Frontend
- The frontend consists of 16 filters
- Each filter output is mapped one-to-one to a neuron in the first neural layer
- There is no fan-in or fan-out at this stage
In software, this is modeled as a synapse with a diagonal 16×16 weight matrix. This abstraction is provided in the frontend reference implementation.
See: reference/models for the software mapping of the filter bank.
Neural Cores
After the frontend, the chip contains:
- 4 cores
- 64 neurons per core
- Total neurons: 256
Each core supports:
- Fully connected feedforward connections (intra- and inter-core)
- Optional recurrent connections, which are:
- All-to-all
- Restricted to neurons within the same core
Note
This doesn't constrain that each layer has to be composed of less than 64 neurons, since layer's neurons can be split across cores.
Neuron Model (High-level)
The neuron model differs from ideal software neurons in a few key aspects:
- A single fixed firing threshold is used across the entire network
- The threshold value cannot be changed per layer or per neuron
- Membrane potential is strictly non-negative
- Negative voltages are clipped by design
These constraints reflect the physical implementation of the neuron circuits on chip.
Non-Idealities (Overview)
The chip exhibits non-idealities typical of analog neuromorphic hardware, including:
- Synaptic weight mismatch
- Leak current (time constant) mismatch
These effects can be explicitly modeled in software using the NWAVE library. The next section describes these constraints in more detail and how to account for them.