Abstract
In this paper, a multistable modified fourth-order autonomous Chua’s chaotic system is investigated. In addition to the dynamic characteristics of the third-order Chua’s chaotic system itself, what interests us is that this modified fourth-order autonomous Chua’s chaotic system has five different types of coexisting attractors: double-scroll, single band chaotic attractor, period-4 limit cycle, period-2 limit cycle, and period-1 limit cycle. Then, an inductorless modified fourth-order autonomous Chua’s chaotic circuit is proposed. The active elements as well as the synthetic inductor employed in this circuit are designed using second-generation current conveyors (CCIIs). The reason for using CCIIs is that they have high conversion rate and operation speed, which enable the circuit to work at a higher frequency range. The Multisim simulations confirm the theoretical estimates of the performance of the proposed circuit. Finally, using RK-4 numerical algorithm of VHDL 32-bit IQ-Math floating-point number format, the inductorless modified fourth-order autonomous Chua’s chaotic system is implemented on FPGA for the development of embedded engineering applications based on chaos. The system is simulated and synthesized on Virtex-6 FPGA chip. The maximum operating frequency of modified Chua’s chaotic oscillator based on FPGA is 180.180 MHz. This study demonstrates that the hardware-based multistable modified fourth-order autonomous Chua’s chaotic system is a very good source of entropy and can be applied to various embedded systems based on chaos, including secure communication, cryptography, and random number generator.
Highlights
Nonlinear phenomena widely exist in natural science, engineering technology, and social science
Many problems in complex networks [1,2,3,4,5,6,7], memristor [8,9,10,11], electronic circuits [12,13,14,15], image processing [16,17,18,19,20,21], economics [22], and other fields can be attributed to the study of nonlinear systems
Chaos is a special state of motion in a nonlinear system, which is a random-like behavior generated by a deterministic system and is extremely sensitive to initial values and highly dependent on them [23,24,25,26,27,28]
Summary
Nonlinear phenomena widely exist in natural science, engineering technology, and social science. There exist several studies related to fourth-order autonomous Chua’s chaotic circuits [70,71,72,73]. In [90], by the help of fourth-order of RK4 method, Sundarapandian-Pehlivan chaotic system was proposed in VHDL 32-bit IEEE 754-1985 floating-point number standard on Virtex-6 FPGA chip. The RK-4 method in a hardware description language (VHDL) is used to model the modified fourth-order autonomous Chua’s chaotic system, and the model is tested comprehensively on Xilinx Virtex-6 FPGA chip.
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