{
  "schema": "semiagora.sram-memory-depth.v1",
  "version": "2026-08-12-v60",
  "experiment_id": "SA-MEM-DEPTH-ASSIST-001",
  "title": "SRAM assist taxonomy replay",
  "execution_mode": "precomputed-only",
  "model_boundary": "Educational replay built from rights-clean synthetic and analytic data. It is not a measured macro, post-layout SRAM, foundry characterization, or product signoff result.",
  "metric_contract": {
    "name": "assist taxonomy tradeoff card",
    "input_axes": [
      "assist family",
      "write margin gain",
      "read stability delta",
      "energy index"
    ],
    "observation": "write assist and read assist move different margins and may harm a neighboring mode",
    "pass_rule": "no assist is selected globally; the replay classifies tradeoffs and required evidence"
  },
  "cases": [
    {
      "id": "assist-baseline",
      "technique": "baseline write",
      "knob_family": "none",
      "write_margin_gain_mv": 0,
      "read_stability_delta_mv": 0,
      "energy_index": 1,
      "coupling_risk": "low",
      "interpretation": "reference case before assist language is added"
    },
    {
      "id": "assist-cell-vdd-collapse",
      "technique": "cell VDD collapse during write",
      "knob_family": "write assist",
      "write_margin_gain_mv": 92,
      "read_stability_delta_mv": -34,
      "energy_index": 1.08,
      "coupling_risk": "medium",
      "interpretation": "helps write-ability by weakening the latch during a controlled write window"
    },
    {
      "id": "assist-wordline-boost",
      "technique": "wordline boost",
      "knob_family": "write assist",
      "write_margin_gain_mv": 76,
      "read_stability_delta_mv": -49,
      "energy_index": 1.16,
      "coupling_risk": "high",
      "interpretation": "strengthens access devices but raises read-disturb and reliability caution language"
    },
    {
      "id": "assist-negative-bitline",
      "technique": "negative bitline",
      "knob_family": "write assist",
      "write_margin_gain_mv": 118,
      "read_stability_delta_mv": -18,
      "energy_index": 1.24,
      "coupling_risk": "high",
      "interpretation": "improves dynamic write-ability while adding driver, coupling, and reliability caution"
    },
    {
      "id": "assist-wordline-underdrive",
      "technique": "wordline underdrive during read",
      "knob_family": "read assist",
      "write_margin_gain_mv": -22,
      "read_stability_delta_mv": 64,
      "energy_index": 0.96,
      "coupling_risk": "medium",
      "interpretation": "protects read stability but can cost read current and access time"
    }
  ],
  "derived_metrics": {
    "case_count": 5,
    "write_assist_count": 3,
    "read_assist_count": 1,
    "strongest_write_gain_mv": 118,
    "largest_read_stability_gain_mv": 64,
    "highest_energy_index": 1.24
  },
  "verification": {
    "write_assists_improve_write_margin_in_this_replay": true,
    "read_assist_improves_read_stability_in_this_replay": true,
    "every_case_has_tradeoff_language": true,
    "no_recipe_or_voltage_setting_is_published": true
  },
  "limitations": [
    "The assist table is a vocabulary and tradeoff replay; it is not a recommended SRAM assist design.",
    "Numbers are normalized teaching values and must not be copied into a macro or chip implementation.",
    "Driver circuits, boost generators, reliability stress, half-select behavior, timing closure, and variation are outside this dataset.",
    "A real assist decision needs foundry models, array context, measurements, aging review, and product constraints."
  ],
  "sources": [
    {
      "label": "UCLA eScholarship SRAM sense amplifier thesis",
      "url": "https://escholarship.org/content/qt0xn2r2wx/qt0xn2r2wx_noSplash_78b1af6aa1f3f19975d8ea05d02b6c16.pdf",
      "note": "Public thesis used for offset, attenuation, control-timing, and sense-amplifier vocabulary."
    },
    {
      "label": "Grossar et al. SRAM read stability and write-ability",
      "url": "https://lirias.kuleuven.be/retrieve/109654",
      "note": "Public paper used for read-stability, write-ability, SNM, and N-curve vocabulary."
    },
    {
      "label": "NVIDIA reverse write assist and SRAM VMIN paper",
      "url": "https://research.nvidia.com/sites/default/files/pubs/2014-03_A-Reverse-Write/ISQED14.pdf",
      "note": "Public paper used to anchor assist, reverse assist, VMIN, guardband, and canary vocabulary."
    },
    {
      "label": "CS61C average memory access time notes",
      "url": "https://notes.cs61c.org/content/caches-intro/amat/",
      "note": "Public course note used for hit time, miss rate, miss penalty, and AMAT vocabulary."
    }
  ]
}