High-resolution time-to-digital converters (TDCs) with a bidirectional encoder

TL;DR

This paper presents a high-resolution FPGA-based TDC using wave union, dual-sampling, and sub-TDL techniques, achieving 0.4 ps resolution and 3.06 ps RMS precision suitable for scientific applications.

Contribution

It introduces a novel combination of wave union, dual-sampling, and sub-TDL methods with a bidirectional encoder for high-resolution TDCs in FPGA.

Findings

Achieves 0.4 ps resolution at 450 MHz sampling rate

Attains 3.06 ps RMS precision in best-case scenarios

Demonstrates suitability for particle physics and biomedical imaging

Abstract

A high-resolution time-to-digital converter (TDC) based on wave union (four-edge WU A), dual-sampling, and sub-TDL methods is proposed and implemented in a 16-nm Xilinx UltraScale+ field-programmable gate array (FPGA). We combine WU and dual-sampling techniques to achieve a high resolution. Besides, we use the sub-TDL method and the proposed bidirectional encoder to suppress bubbles and encode four-transition pseudo thermometer codes efficiently. Experimental results indicate the proposed TDC achieves a 0.4 ps resolution with a 450MHz sampling clock and a 3.06 ps RMS precision in the best-case scenario. These characteristics make this design suitable for particle physics, biomedical imaging (such as positron emission tomography, PET), and general-purpose scientific instruments.