A subthreshold-CMOS chaotic oscillator

This paper reports on the design of a subthreshold-CMOS chaotic oscillator based on Chua's circuit. The circuit is autonomous and generates chaotic signals from three state variables in a manner analogous to a Chua circuit. Previous CMOS IC versions of the Chua circuit operate above threshold and make use of capacitors over 200 times larger than the subthreshold design. Also, this design is based on fundamentally nonlinear subthreshold building blocks permitting flexible adjustment of bifurcation parameters for investigation of complex phenomena not present in a piecewise linear model. Finally, this design incorporates all necessary elements on chip, eliminating the need for an external resistor. The combination of reduced size and flexible nonlinearity make this design suitable for a single-chip VLSI synthesis of complex circuits making use of chaotic signals, including coupled maps generating spatio-temporal chaos and systems exploiting chaos synchronization.