We introduce the waveform capture device (WCD), a flexible measurement system capable of recording complex digital signals on trillionth-of-a-second (ps) time scales. The WCD is implemented via modular code on an off-the-shelf field-programmable gate-array (FPGA, Intel/Altera Cyclone V), and incorporates both time-to-digital converter (TDC) and digital storage oscilloscope (DSO) functionality. The device captures a waveform by taking snapshots of a signal as it propagates down an ultra-fast transmission line known as a carry chain (CC). It is calibrated via a novel dynamic phase-shifting (DPS) method that requires substantially less data and resources than the state-of-the-art. Using DPS, we find the measurement resolution - or mean propagation delay from one CC element to the next - to be 4.91 +/- 0.04 ps (4.54 +/- 0.02 ps) for a pulse of logic high (low). Similarly, we find the single-shot precision - or mean error on the timing of the waveform - to be 29.52 ps (27.14 ps) for pulses of logic high (low). We verify these findings by reproducing commercial oscilloscope measurements of asynchronous ring-oscillators on FPGAs, finding the mean pulse width to be 0.240 +/- 0.002 ns per inverter gate. Finally, we present a careful analysis of design constraints, introduce a novel error correction algorithm, and sketch a simple extension to the analog domain. We also provide the Verilog code instantiating the our design on an FPGA in an Appendix, and make our methods available as an open-source Python library at https://github.com/Noeloikeau/fpyga.
翻译:我们引入了波形捕捉装置(WCD),这是一个灵活的测量系统,能够记录数万分之一秒(ps)时间尺度上的复杂数字信号。WCD是在现成的现场可编程门阵列(FPGA, Intel/Altera Crapal V)上通过模块代码执行的,并且既包括时间对数字转换器(TDC),也包括数字存储显微镜(DSO)功能。这个装置通过在超快传输线下传动被称为传承链(CC)时的信号缩影来捕捉波形。它通过新颖的动态阶段转换(DPS)方法来校准。使用DPS,我们发现测量分辨率解析解析器-或从一个CC元素到下一个的传播延迟-4.91+/0.04 ps (4.54+/-fo.02 ps) 来提供一个新逻辑高的脉冲(low) 脉冲(我们发现一个直径的直径直径的直径精确度和直径直径直径的直径直径直径直径直径直径直径直径直径直径(29) 或直径直径直的直径直径直径直路路的直径直径直路路路路路路路路路路路路路路路路路路路的根根根根的直的直的根根根根根根根的直径)。