A 1.7 ps Equivalent Bin Size and 4.2 ps RMS FPGA TDC Based on Multichain Measurements Averaging Method
A 1.7 ps Equivalent Bin Size and 4.2 ps RMS FPGA TDC Based on Multichain Measurements Averaging Method
复制标题
基于多链测量平均方法的 1.7 ps 等效 Bin 大小和 4.2 ps RMS FPGA TDC
DOI：
10.1109/tns.2015.2426214
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发表时间：
2015-06-01
影响因子：
1.8
通讯作者：
Liu, Weiyue
中科院分区：
文献类型：
--
作者：
Shen, Qi;Liu, Shubin;Liu, Weiyue
在40 nm工艺Virtex-6 FPGA上实现了一种基于多链测量平均法的高精度、高分辨率时间数字转换器（TDC）。详细的理论分析和基于完整TDC模块的MATLAB仿真结果表明，该方法可以克服普通抽头延迟链固有单元延迟对分辨率的限制，在不增加死区时间的情况下，提高了分辨率和精度。试验结果与仿真结果吻合较好。在这种TDC中，输入信号同时连接到多个抽头延迟链（链的数量为M），并且每个链只是一个普通的TDC，并为命中信号生成时间戳。因此，总共应该获得M个时间戳，在平均之后，给出最终的时间戳。在M = 16的情况下，实现了具有1.7ps等效单元尺寸、1.5ps平均单元尺寸和4.2ps RMS的TDC，其性能远远优于由具有42.3ps等效单元尺寸、24.0ps平均单元尺寸分辨率和13.2ps RMS精度的单抽头延迟链构成的普通TDC。等效面元尺寸和平均面元尺寸的比较表明，较大的M值可以改善非线性。由于采用了真实的时间积分非线性（INL）校准和平均计算，多链TDC对工艺电压和温度（PVT）变化几乎不敏感。
A high precision and high resolution time-to-digital converter (TDC) based on multichain measurements averaging method is implemented in a 40 nm fabrication process Virtex-6 FPGA. The results of the detailed theoretical analysis and the simulation with the MATLAB tool based on a complete TDC module show that the resolution limitation determined by the intrinsic cell delay of plain tapped-delay chain can be overcame, which results in an improvement on both resolution and precision without increasing the dead time. The test results agree with the simulation results quite well. In such a TDC, the input signal is connected to multiple tapped-delay chains simultaneously (the number of the chains is M), and each chain is just a plain TDC and generates a timestamp for a hit signal. Therefore, M timestamps should be obtained in total, which, after averaging, give the final timestamp. A TDC with 1.7 ps equivalent bin size, 1.5 ps averaged bin size and 4.2 ps RMS has been implemented with M being 16, which performs much better than the plain TDC constructed of a single tapped delay chain having 42.3 ps equivalent bin size, 24.0 ps averaged bin size resolution and 13.2 ps RMS precision. The comparisons of equivalent bin size and averaged bin size show that the nonlinearity is improved with a larger M. Due to the real time integral nonlinearity (INL) calibration and averaging calculation, the multichain TDC is almost insensitive to the process voltage and temperature (PVT) variations.