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README.md

WRPLL simulation

A time domain simulation for WRPLL

Installing dependencies

Nix:

nix develop

Others:

python -m venv .venv
source .venv/bin/activate
(venv) pip install -r requirements.txt

Quick start

  • Three notebook examples are included

    1. helper_PLL_example.ipynb : helper PLL only
    2. main_PLL_example.ipynb : main PLL only with a user specific helper frequency
    3. both_PLL_example.ipynb : main and helper PLL
  • RAM usage and execution time estimate for simulation ONLY

    1. 100,000,000 time steps: 6GiB RAM and 12 seconds

    2. 200,000,000 time steps: 11GiB RAM and 20 seconds

    3. 300,000,000 time steps: 16GiB RAM and 35 seconds


WRPLL formulas
  • Assume the difference between f_{main}, f_{gtx} is very small

    • Let f_{in} = f_{main} = f_{gtx}

    • f_{helper} = f_{in} * \dfrac{N-1}{N}

    • f_{beat} = f_{in} - f_{helper} = \dfrac{f_{in}}{N}

  • Main and helper Si549 DCXO ADPLL setting

    • ADPLL = \dfrac{\Delta f_{outppm}}{0.0001164}

Limitation

As the simulation is not cycle nor delay accurate, there will be more glitches than the hardware implementation