A voltage-controlled chaotic oscillator based on carbon nanotube field-effect transistor for low-power embedded systems

This paper presents a compact and low-power-based discrete-time chaotic oscillator based on a carbon nanotube field-effect transistor implemented using Wong and Deng＇s well-known model. The chaotic circuit is composed of a nonlinear circuit that creates an adjustable chaos map, two sample and hold cells for capture and delay functions, and a voltage shifter that works as a buffer and adjusts the output voltage for feedback. The operation of the chaotic circuit is verified with the SPICE software package, which uses a supply voltage of 0.9 V at a frequency of 20 kHz. The time series, frequency spectra, transitions in phase space, sensitivity with the initial condition diagrams, and bifurcation phenomena are presented. The main advantage of this circuit is that its chaotic signal can be generated while dissipating approximately 7.8 μW of power, making it suitable for embedded systems where many chaos-signal generators are required on a single chip.

Effect of Temperature on a Two-Phase Clock-Driven Discrete-Time Chaotic Circuit

The effects of temperature on a two-phase clock-driven discrete-time chaotic circuit are presented.The circuit for temperature analysis consists of two switches for sample and hold,a source follower,and a nonlinear function for nonlinearity in the feedback.The chaotic dynamics of this circuit,such as time series,state transitions,frequency spectra bifurcation diagrams and Lyapunov exponents are analyzed as functions of the temperature.It is confirmed that the dynamics of the chaotic circuit have a temperature dependence.Further,we find that the circuit can generate discrete chaotic signals only within specific temperature regions.

Bifurcation Analysis of the Voltage Controlled Photosensitive Chaotic Oscillator

A photosensitive chaotic oscillator which can be controlled with light illumination under various control voltage levels is proposed.The oscillator consists of a photodiode for the light input,clock switches and capacitors for the sample and hold function,a nonlinear function that creates an adjustable chaos map,and a voltage shifter that adjusts the output voltage for feedback.After optimizing the photodiode sub-circuit by using an available photodiode model in PC-based simulation program with integrated circuit emphasis to obtain a suitable output,the full chaotic circuit is verified with standard 0.6-μm complementary metal oxide semiconductor parameters.Chaotic dynamics are analyzed as a function of the light intensity under different control voltage levels.The time series,frequency spectra,transitions in state spaces,bifurcation diagrams and the largest Lyapunov exponent are improved.

Stability of operation versus temperature of a three-phase clock-driven chaotic circuit

We evaluate the influence of temperature on the behavior of a three-phase clock-driven metal–oxide–semiconductor （MOS） chaotic circuit. The chaotic circuit consists of two nonlinear functions, a level shifter, and three sample and hold blocks. It is necessary to analyze a CMOS-based chaotic circuit with respect to variation in temperature for stability because the circuit is sensitive to the behavior of the circuit design parameters. The temperature dependence of the proposed chaotic circuit is investigated via the simulation program with integrated circuit emphasis （SPICE） using 0.6-μm CMOS process technology with a 5-V power supply and a 20-kHz clock frequency. The simulation results demonstrate the effects of temperature on the chaotic dynamics of the proposed chaotic circuit. The time series, frequency spectra, bifurcation phenomena, and Lyapunov exponent results are provided.