Sensitivity study and improvements on a nonlinear resistive-type neuron circuit

A generalised VLSI circuit realisation for a nonlinear active resistor-type neuron is proposed that implements a saturating sigmoidal-like function by combining the nonlinear characteristics of NMOS and PMOS transistors. The circuit design is based on using a parameter sensitivity analysis to develop a robust design that will be relatively insensitive to process-parameter variations over the area of the die. The nonlinear resistor has been integrated into a module which realises a programmable digital synaptic weight capability. A neuron is effectively formed from the parallel interconnection that takes place as multiplier outputs are connected to create an input node to the resultant distributed neuron. Designs in 0.35 and 0.8 mu m processes are compared with a conservative 1.2 mu m CMOS implementation.