| High-speed sampling is widely used in communications, radar and other fields. However, a single ADC can not meet the needs of high sampling rate and high resolution at same time. We can improve the sampling rate without reducing the resolution by applying a technology called TIADC, which using several ADCs sampling a signal simultaneously. The disadvantage of TIADC is that the difference between ADCs will lead mismatchs between sampling channels. These mismatchs include an offset mismatch caused by different bias voltages, a gain mismatch caused by different gains, a time mismatch caused by difference phases of sampling clocks. The three mismatchs will demage the performance of the system.Finally we have carried out a TIADC system which has 8 channels. And the sampling rate of the system is 8 GSPS. In order to correct the three mismatchs, we have done the following work in this paper.1) We have studied the relationship between the channel-mismatchs and the number of channels and sampling rate.According to the characteristics of the system, we have analyzed the affect to the system cause by channel-mismatchs. Finally we have proposed a solution to correct.2) In this paper, we have also compared several methods of acquiring channel-mismatchs and have selected a most appropriate method called sin-fit. We have analysed the advantages and disadvantages of the sin-fit method and then have proposed an improved sin-fit method which introduce the frequency of the signal as a parameter to estimate.3) According to the characteristics of the three mismatchs and the characteristics of the system, we have propsed a synchronization method called to autosync to synchronize data from different channels. And we have alse proposed a comprehensive correction method by combining adders, multipliers, and FARROW structured filters. Finally we have carried out a series of experiments to verify the validity of the methods mentioned above. |
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