Generation of Chaotic Signals Using Current-Mode Techniques

Abstract

This article presents architectures and circuit techniques to design chaotic piecewise-linear discrete maps in CMOS VLSI. Maps are presented for white and 1/fγ noise generation, as well as to display bidimensional strange attractors. The proposed circuits use only MOS transistors and thus are suitable for implementation in standard CMOS technologies containing only one poly layer. A family of CMOS building blocks for piece-wise-linear function interpolation in current-domain is presented based upon the use of a current switch. Novel circuit strategies are given for improved current-switch performance as well for high-resolution current comparison. These strategies can be used for the design of chaotic current-mode circuits, as well for the representation problem via basis functions in feedforward neural networks and fuzzy inference engines. Also, an innovative scheme for adaptive feedthrough cancellation in dynamic current mirrors is presented, which aids in reducing the most significant error source in chaotic current-mode discrete maps. The article includes experimental results from monolithic n-well CMOS 1.6 μm prototypes of the building blocks as well as complete systems; in particular, a chaotic neuron according to the Aihara's model and a broadband white noise generator.