Resynchronization & metastability

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Metastability is an undesirable non-equilibrium electronic state that can persist for a long period of time

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Poisson stochastic process

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Synchronizer effect – latency uncertainty

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simulation of DFF

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The typical flip-flops comprise master and slave latches and decoupling inverters.

In metastability, the voltage levels of nodes A and B of the master latch are roughly midway between logic 1 (VDD) and 0 (GND)

master latch enter metastability

In fact, one popular definition says that if the output of a flip-flop changes later than the nominal clock-to-Q propagation delay, then the flip-flop must have been metastable

sweep \(\Delta t_{D \to \space \text{CK}}\)

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transient noise analysis @ \(\Delta t_{D \to \space \text{CK}} = -3.444525p\)

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zoom out

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Noise Seed—Seed for the random number generator (used by the simulator to vary the noise sources internally). Specifying the same seed allows you to reproduce a previous experiment. The default value is 1.

reference

Yvain Thonnart, CEA-LIST. ISSCC2021 T8: On-Chip Interconnects: Basic Concepts, Designs and Future Opportunities [https://www.nishanchettri.com/isscc-slides/2021%20ISSCC/TUTORIALS/ISSCC2021-T8.pdf]

R. Ginosar, "Metastability and Synchronizers: A Tutorial," in IEEE Design & Test of Computers, vol. 28, no. 5, pp. 23-35, Sept.-Oct. 2011 [https://webee.technion.ac.il/~ran/papers/Metastability-and-Synchronizers.IEEEDToct2011.pdf]

Amr Adel Mohammady. Clock Domain Crossing [linkedin]

Steve Golson. Synchronization and Metastability [https://trilobyte.com/pdf/golson_snug14.pdf]

Kinniment, D. J. Synchronization and arbitration in digital systems. John Wiley & Sons Ltd (2007).

Synchronizers And Data FlipFlops are Different [pdf]

S. Beer, R. Ginosar, M. Priel, R. Dobkin and A. Kolodny, "The Devolution of Synchronizers," 2010 IEEE Symposium on Asynchronous Circuits and Systems, Grenoble, France, 2010 [pdf]

赵启林 klin, Metastability [https://picture.iczhiku.com/resource/eetop/SHKSFADwZerLPBXN.pdf]

Asad Abidi. ISSCC 2023: Circuit Insights "The CMOS Latch" [https://youtu.be/sVe3VUTNb4Q&t=681]

Matt Venn. Interactive flip flop simulation [https://github.com/mattvenn/flipflop_demo]