A neuromime in VLSI

Using conventional very large scale integration (VLSI) technology, a flexible and comprehensive neuromime circuit has been implemented in silicon for the purpose of modeling nerve networks from living organisms. Based on the "integrate-and-fire" model of neuronal threshold, the circuit was fabricated in two-micron CMOS with double-level metal. It occupies 0.6 square millimeters of die area, and requires only a few passive biasing components off-chip. The neuromime circuit offers many continuously variable parameters, including excitatory and inhibitory sensitivity and persistence, refractory duration and strength, and overall speed of operation. The circuit offers free and continuous access to waveforms for presynaptic membrane potential, postsynaptic membrane potential, and threshold potential. As such, it is amenable to many secondary behavioral characteristics, such as postinhibitory rebound, fatigue, facilitation, and accommodation. Being power-efficient, compact, and noise immune, it is ideal for assembly into networks and interfacing to biological counterparts.