A high-precision VLSI winner-take-all circuit for self-organizing neural networks

The design and implementation of a high-precision VLSI winner-take-all (WTA) circuit that can be arranged to process 1024 inputs are presented. The cascade configuration can be used to significantly increase the competition resolution and maintain high-speed operation for a large-scale network. The total bias current increases in proportion to the number of circuit cells so that a nearly constant response time is achieved. A unique dynamic current steering method is used to ensure that only a single winner exits in the final output. Experimental results for a prototype chip fabricated in a 2- mu m CMOS technology show that a cell can be a winner if its input is larger than those of the other cells by 15 mV. The measured response time is around 50 ns at a 1-pF load capacitance. This analog winner-take-all circuit is a key module in the competitive layer of self-organizing neural networks.>