中心博士生秦睿恒的工作——Decoupling and one-time elimination of timing skew in time-demultiplexing photonic analog-to-digital converter for high-resolution wideband signal acquisition（面向高精度宽带信号采集的时分解复用型光子模数转换系统中时序偏移问题的解耦和一次性校准）的相关成果近期被OPTICS LETTERS期刊接收发表，该工作得到了国家重点研发计划（2019YFB2203700，2022YFB2803302）、国家自然科学基金（T2225023，62205202）、以及上海市青年科技英才杨帆计划（No. 22YF1420200）的部分资助。面向未来电子信息系统对复杂宽带信号的高精度采集需求，波形数字化过程中解复用信号和采样信号之间的时序偏移问题极大地增加了光子模数转换系统(PADC)的设计难度，对时序偏移的精确提取与高效补偿需求也日益凸显。本研究对比了从传统交织型电子模数转换系（TI-EADC）统到PADC的典型方案并分析了时序偏移问题的影响，证明了时分解复用型PADC在采样精度和校准灵活度上的优势。针对时分解复用型PADC，本工作提出了一种矢量解耦方法，利用系统相频响应实现对每一级解复用产生的时序偏移的精确提取。此外，本研究证明时序偏移的补偿可以利用光真延时效应在光域实现，这使得瞬变宽带信号的校准可以通过几个单频信号一次性实现。在实验验证方面，我们搭建了一台40GSa/s采样率的8通道PADC样机，并利用样机验证了提出的校准方法的效果。经过校准后，我们将系统0-20GHz输入频率下的无杂散动态范围提升至约55dB，有效位数提升至约8bit。该有效位数比近期发表的时分解复用型PADC提升了约1bit。因此，本研究所提出的方法和经过验证的系统性能使得时间解复用PADC成为高分辨率宽带信号采集领域的有竞争力的解决方案，并有望应用于下一代雷达和通信系统。
摘要: Temporal alignment between demultiplexing signal and sampled signal for complex wideband signals greatly increases the difficulty of designing high-speed and high-resolution photonic analog-to-digital converters (PADCs). We present a vector description to decouple timing skew from the phase frequency response in time-demultiplexing PADC. We demonstrate that the calibration can be optically implemented with true time delay effects and the broadband input can be one-time calibrated through several single-frequency signals. For verification, we configure out a 40 GSa/s PADC with 8 interleaved sub-channels. The timing skew-induced spurs across the whole Nyquist band are effectively suppressed, making the PADC acquire wideband signal with 16 GHz instantaneous bandwidth. The spurious free dynamic range (SFDR) is enhanced to ~55 dB, and the effective number of bits (ENOB) is improved from ~5.5 bits to ~8 bits within 20 GHz. It is nearly 1 bit better than the recently reported time-demultiplexing PADC under the comparable input frequencies.