A High Resolution ADC Model Combined Pipeline and Sigma -Delta Oversampling Architecture

Data acquisition system is a key instrument to convert analog signals to digital signals in geophysics. To match high resolution sensors in seismometers systems, high resolution analog-digital conversion (ADC) is deployed in data acquisition system. Classical high resolution ADC models are based on architecture of Σ-Δ oversampling or pipeline ADC architecture separately. Those ADC architectures have following problems: increase power consumption, reduce linearity of modulators, depend on design of complex circuit, and the resolution is not easily regulated. To solve those problems and promote resolution of ADC, a novel architecture design is presented, which design principle is based on mathematical formulations combined advantages both previous pipeline and oversampling ADC architecture. A simple and mathematical combined ADC analysis model is presented. Using this model, this paper analyzes theoretically the various sources of noise of the adverse effects of the whole ADC architecture. Based on an assessment of noise simulation algorithm, an amended theoretical model is proposed. The results represent that noises level of integrator and subtractor in first level of combined model determine the whole performance. By controlling the noise level from these two components to less than 10−7V/✓Hz, the resolution of whole data acquisition system can achieve reservation resolution of 150 dB.