To Improve The Performance Of Pipeline - Adc Resolution And Sfdr Internal Dither Technology Research

With the direct sampling of RF signals, the software defined radio system will be the main trend of the future radio develop, Pipeline ADC is widely used in software radio systems because of its high speed and high precision characteristics. However, influenced by various factors of non-ideal circuit, pipelined ADC’s dynamic performance has been extremely limited, especially the deterioration of the SFDR p, and it will result larger adjacent channel interference in the radio system, the Dither technique will be an effective means to improve the SFDR of the ADC. The spurious wave components induced by coherent quantitative sampling and nonlinear in ADC will be suppressed by use of Dither. In addition, Dither technique can also be used to improve the actual resolution of the ADC combining with statistical averaging technique.This paper first introduces the basic principles and detailed methods for Dither teshnologyto improve the ADC’s resolution, and gives a special Dither signal making the statistical average times to a minimum, and shows that the actual resolution of the ADC was improved by Dither with The simulation.Then the paper analyze the main factors to affect the SFDR performance of the pipelined ADC, The theory form and mathematical derivation of the principle for Dither technology to improve the ADC’s SFDR,12bit pipeline ADC behavior-level error simulation model and internal pipelined ADC Dither simulation system were built in Simulink, and analyze the situation about spurious free dynamic range improves in two pipelined ADC internal Dither structure by simulation.After the introduction of Dither, the input dynamic range of ADC will be decreased, for this situation the paper gives two solutions in this article and verify its correctness by simulation.In this paper, the Dither technology can effectively improve the resolution and SFDR of the ADC, but the improvement to the resolution of the ADC is a trade-offs between the speed and accuracy of the ADC, the Dither Added in the inner of pipelined ADC can be easily added and easily to get rid of, will not generate much additional noise, it can enable the ADC’s SFDR increase by more than10dB in the case of ADC’s signal noise and distortion ratio decreases no more than1dB.