Study Of Chaotic A/D Converter

A fundamental underlying property in a chaotic system is sensitive dependence on initial conditions and parameters. Sensitive dependence on initial conditions means that little difference on initial conditions will lead to great changes on chaotic orbit. The application of chaos theory in designs of A/D converter is a potential field. The basic idea of the chaotic A/D converter is that, a signal sample is as an initial condition of the chaotic system, a corresponding orbit will be generated and its chaotic coding will be gotten according to symbol dynamics. Because of sensitivity of the chaotic system, two very close initial values will produce two obviously separate chaotic orbits. So the chaotic A/D converter can achieve high resolving power.∑-A A/D is a very potential A/D converter in CMOS mixed signal design at present. In essence, it is based on circle mapping from its non-linear dynamic system. An active integral chaotic A/D converter based on sawtooth mapping is presented in this paper. It gets rid of nonlinear distortion of mapping function in constant-voltage mode and avoids defect of constant-current source working on switching states, and can be easily implemented in integrated circuit using switched-capacitor circuits. Its architecture is simpler than ∑-△A/D converter without oversampling and decimation. Effects of offset voltage, offset current, charge-discharge rate and switching delay in chaotic circuits are discussed in this paper. The relationship of convert speed and precision is also described from experimental data.