Application and Comparison of FPGA-Based Carry Chain TDC and DDMTD Schemes in High-Precision Time Synchronization

Area of Science:

• Electrical Engineering
• Digital Signal Processing
• Measurement Science

Background:

• High-precision phase difference measurement is crucial for applications like time-frequency transmission and signal synchronization.
• Traditional methods face limitations in temperature stability and measurement accuracy.
• Field-programmable gate arrays (FPGA) offer a flexible platform for advanced measurement solutions.

Purpose of the Study:

• To propose and evaluate two novel high-precision phase difference measurement schemes utilizing FPGA technology.
• To address the shortcomings of existing methods concerning temperature stability and accuracy.
• To compare the performance of an eight-parallel-multi-carry chain time-to-digital converter (TDC) against a single-carry chain TDC and a digital dual-mixer time difference (DDMTD) module.

Main Methods:

• Implementation of an eight-parallel-multi-carry chain TDC module on an FPGA.
• Development of a digital dual-mixer time difference (DDMTD) measurement module.
• Comparative analysis of measurement accuracy, resolution, and temperature stability under varying conditions.
• Utilizing MMCM dynamic phase-shifted signals for phase difference evaluation.

Main Results:

• At room temperature, the single-carry chain TDC achieved a measurement error of 4.7-6.0 ps, outperforming the DDMTD's 20-75 ps error.
• The eight-parallel-multi-carry chain TDC demonstrated superior accuracy (within 4.6 ps error at room temp), resolution (0.833 ps vs. 6.329 ps), and temperature stability (0.000564 ps/°C vs. 0.002127 ps/°C) across a 10 °C to 100 °C range.
• The eight-parallel-multi-carry chain TDC consistently outperformed the single-carry chain TDC in accuracy, resolution, and temperature stability under diverse temperature conditions.

Conclusions:

• The eight-parallel-multi-carry chain TDC offers significant improvements in precision, resolution, and temperature stability for FPGA-based phase difference measurements.
• Both proposed FPGA schemes provide viable alternatives to traditional methods, with the multi-carry chain TDC being preferable for demanding applications.
• The study provides valuable insights for optimizing high-precision phase difference measurement techniques on FPGA platforms, considering implementation complexity and robustness.