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5 picoseconds and the countdown continues!

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A time-to-digital converter (TDC) is an electronic circuit that converts time into a digital code used by digital circuits (a very precise stopwatch). The objective is to measure time with the best possible precision, of the order of magnitude of a picosecond, or a thousandth of a billionth of a second (10th-12 seconds). There are many TDC architectures, but few can provide good performance for the five key requirements of low area, low power consumption, low timing jitter, low dead time, and low cost.


This invention is a game-changer for TDCs. Its objective is to achieve laboratory performance for time precision while benefiting from the advantages of integrated circuits in terms of low cost and low power consumption. The preferred architecture is the Vernier type TDC based on ring oscillators. Modifications to current architectures are required to minimize the number of cycles while reducing circuit size. This invention uses several successive Vernier processes based on a single reference oscillator. It offers a reference oscillator + 1 additional oscillator per Vernier process. This concept of multiple Verniers greatly minimizes the number of Vernier cycles (reduction factor up to 50), which is critical for low timing jitter measurements. It therefore makes it possible to reduce the number of revolutions carried out, to improve the temporal precision and to reduce the conversion time, without losing the "timing" information.


  • Considerable reduction in the number of Vernier cycles compared to a single Vernier TDC.

  • Improved timing accuracy (~1ps)

  • Circuit miniaturization (e.g.: 256 TDCs in a 1mm2 detector)

  • Reduced conversion time. Reduced energy consumption.

  • A faster TDC at a better price - see Figure 1.

  • Timing accuracy similar to tabletop TDCs, but with minimal power consumption and lower cost – enabling competition in the LiDAR and 3D imaging systems markets.

  • More accurate than all other IC TDCs.

  • Much cheaper than all other lab TDCs.


Applications that will benefit from the improved features of this new TDC are numerous:

  • Medical imaging

  • Benefits – lower patient dose, better contrast, higher throughput and real-time 3D reconstruction.

  • Proximity sensors, 3D cameras and automotive LiDAR

  • Advantages – Better spatial resolution and better temporal precision.

  •  Quantum cryptography

  • Benefits – Miniaturization of systems for large-scale production.

  • Laboratory equipment

  • Advantages – Significant reduction in manufacturing costs.

  • The markets for TDCs are varied and immense:

  • Consumer 3D cameras - ~$13.8 billion by 2023 o Industrial and automotive LiDAR - ~$6.3 billion by 2023

  • Medical imaging - ~US$35 billion by 2022

  • Quantum cryptography - ~$0.94 billion by 2022

  • Fluorescence microscopy - ~$0.53 billion by 2023



TRL 5-6

  • Solution ready to be transferred to industry.

  • 1 Picosecond Goal - Inventors continue their work on improving performance with a 1ps goal.

  • The latest prototype contains several Vernier processes and is ready for demonstration to interested partners.

  • Also developments of systems containing these TDCs with related circuits such as single-photon avalanche diodes (SPADs) and other applications.


  • PCT international patent filed.


Development and collaboration partners. Commercial Partners. Licenses. Investments

Project Director: François Nadeau

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