Current-mode subthreshold MOS implementation of the Herault-Jutten autoadaptive network

The authors explore translinear circuits in subthreshold MOS technology and current-mode design techniques for the implementation of neuromorphic analog network processing. The architecture, also known as the Herault-Jutten network, performs an independent component analysis and is essentially a continuous-time recursive linear adaptive filter. Analog I/O interface, weight coefficients, and adaptation blocks are all integrated on the chip. A small network with six neurons and 30 synapses was fabricated in a 2-μm double-polysilicon, double-metal n-well CMOS process. Circuit designs at the transistor level yield area-efficient implementations for neurons, synapses, and the adaptation blocks. The authors discuss the design methodology and constraints as well as test results from the fabricated chips