Design Of An On-chip Chaotic A/D Converter Fabricated 0.6um CMOS Process

In a mixed signal-processing system, the analog-to-digital converter is always an important component. There are two types of ADC, one is Nyquist ADC ,the other is oversampling ADC. The type of chaotic A/D converter is called Nyquist ADC. Compared to other architectures, the chaotic A/D converter is creditable that the chaotic system is sensitive dependence on initial conditions, therefore, two very close initial value will produce two obviously separate chaotic orbits, so the chaotic ADC can achieve high resolving power by detecting the difference between their orbits.According to the research situation of chaotic sensor principle and chaotic measure circuit, a chaotic A/D converter based on constant-current mode was presented in this paper. The A/D converter was fabricated in 0.6um double-poly double-metal CMOS process. According to bottom-top full custom IC design methodology. The circuit was divided to sub-block based on circuit function, such as sample circuit, compatator, oscillate, digital logical block, reference and bias circuit. Transistor-level schematic of sub-block was created in schematic editor, then spectre simulation of circuit block was used to verify their function. A 14-bit and clock frequency of 500kHz chaotic ADC was presented in this paper.Parameter simulation of system circuit was used to analyze chaotic sensitive dependence on parameter. Effects of offset, switch parastic parameter, the ratio of charge and discharge current ,power noise in chaotic circuit were discussed in this paper.Finally, mask-layout of important circuit such as compatator, digital logical block and oscillate were created in layout Eidtor.The chaotic ADC required simple hardware and was not necessary convert chaotic code to typical binary system.Therefore, it can be applied to design IP core of ADC in SOC.