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基于TIADC技术的波形数字化系统的测试与评估

Testing and Evaluation of a Waveform Digitization System Based on TIADC Technique

  • 摘要: 并行交替采样(Time-Interleaved Analog-to-Digital Conversion, TIADC)可成倍提升采样系统的采样率,是高速波形数字化系统设计中的一项重要技术。然而不同采样通道间存在失配误差,这会使得系统性能相对于单个ADC明显下降,因此TIADC系统设计中还需要对失配误差进行修正。而对TIADC系统进行科学的性能测试与评估是评价系统设计质量以及推进下一步优化设计的必备环节。针对TIADC系统的性能测试与评估,详细介绍了各项性能指标以及测试方法,完成了一个由2片国产高速ADC组成TIADC系统的一系列性能测试,并利用完美重构算法对该系统的失配误差进行了修正。经测试,该系统可实现5 Gsps的等效采样率,并可基于该算法实现宽带内失配误差修正,修正后系统各项动态性能均得到显著提高,其中有效位(Effective Number of Bits, ENOB)性能达9.2 bits@247 MHz,8.9 bits@857 MHz,与单个ADC性能指标相当。

     

    Abstract: Time-Interleaved Analog-to-Digital Conversion(TIADC) is one of the most important techniques in the design of high-speed waveform digitization systems, it can multiple the sampling rate of a sampling system. However, there are mismatch errors between different sampling channels, which will make the dynamic performance of a TIADC system significantly lower than that of a single ADC. Therefore, mismatch errors should be corrected in TIADC system design. To evaluate the quality of the system design and promote the next optimization design, it is necessary to conduct scientific performance test and evaluation on the TIADC system. In this work, aiming at the test and evaluation, the performance indexes and test methods of TIADC system are introduced in detail, a series of performance tests of the system are completed, and mismatch errors are corrected based on perfect reconstruction algorithm. The test results show that the system can achieve an equivalent 5 Gsps sampling rate and can realize mismatch error correction in a wide band based on the proposed mismatch error correction method. After correction, the dynamic performance of the TIADC system is significantly enhanced compared with that without correction. For example, the Effective Number of Bits(ENOB) of the proposed system reaches 9.2 bits at 247 MHz, 8.9 bits at 857 MHz, which is equivalent to the performance index of a single ADC.

     

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