CHUA CIRCUIT - 10 YEARS LATER

More than 200 papers, two special issues (Journal of Circuits, Systems , and Computers, March, June, 1993, and IEEE Trans. on Circuits and Sy stems, vol. 40, no. 10, October 1993), and International workshop on ' 'Chua's Circuit: chaotic phenomena and applications'' at NOLTA '93, an d a book (Edited by R. N. Madan, World Scientific, 1993) on Chua's cir cuit have been published since its inception a decade ago. This review paper attempts to present an overview of these timely publications, a lmost all within the last 6 months, and to identify four milestones of this very active research area. An important milestone is the recent fabrication of a monolithic Chua's circuit. The robustness of this IC chip demonstrates that an array of Chua's circuits can also be fabrica ted into a monolithic chip, thereby opening the floodgate to many unco nventional applications in information technology, synergetics, and ev en music. The second milestone is the recent global unfolding of Chua' s circuit, obtained by adding a linear resistor in series with the ind uctor to obtain a canonical Chua's circuit-now generally referred to a s Chua's oscillator. This circuit is most significant because it is st ructurally the simplest (it contain only 6 circuit elements) but dynam ically the most complex among all nonlinear circuits and systems descr ibed by a 21-parameter family of continuous odd-symmetric piecewise-li near vector fields. The third milestone is the recent discovery of sev eral important new phenomena in Chua's Circuits, e.g., stochastic reso nance, chaoschaos type intermittency, 1/f noise spectrum, etc. These n ew phenomena could have far-reaching theoretical and practical signifi cance. The fourth milestone is the theoretical and experimental demons tration that Chua's circuit can be easily controlled from a chaotic re gime to a prescribed periodic or constant orbit, or it can be synchron ized with 2 or more identical Chua's circuits, operating in an oscilla tory, or a chaotic regime. These recent breakthroughs have ushered in a new era where chaos is deliberately created and exploited for unconv entional applications, e.g., secure communication.