A Data Acquisition System Based On Analog And Digital Dither

Analog to digital converters always act as important roles in high dynamic range data acquisition systems. However, the dynamic range of ADC is diminished due to its nonlinearity. Dither, a very popular technology used in recent years can improve the resolution of ADC and diminish the harmonics caused by quantization error and coherent sampling and thus improving the dynamic range of ADC.Firstly, this dissertation starts with an introduction to the operation principle of analog to digital converters and different kinds of analog to digital converters most popular used. The concept and the cause of quantization error is introduced. Some significant performance indicators related to ADC like differential nonlinearity, integral nonlinearity, spurious-noise free dynamic range and signal to noise ratio are introduced as well.Secondly, this dissertation gives an introduction to dither as well as some circuits to generate a dither signal and presents that with the combination of dither and average the resolution of ADC can be improved and the harmonics caused by differential nonlinearity, quantization error and coherent sampling can be diminished, improving the spurious-noise free dynamic range of ADC.In addition, the results of simulation in MATLAB shows the validity of above conclusion and the spurious-noise free dynamic range can be improved from 26.40 d Bc to 33.71 d Bc.At last, dither circuits are designed in detail and tested with an actual high-speed 10 bits ADC(ADC1061).