micheleandCursor
4403c38d96
Keep both as labelled estimates: no Murata lot curve and no invented Z(f) target without f_sw. Co-authored-by: Cursor <cursoragent@cursor.com>
110 lines
3.8 KiB
Python
110 lines
3.8 KiB
Python
"""HF decoupling coverage — bulk without a small ceramic.
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Without a switching frequency this does not invent a Z(f) target.
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INFO only: HF coverage depends on a ~100 nF close to the pin.
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"""
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from __future__ import annotations
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from backend.pinscopex.models import ComponentType, DesignGraph, Finding, NetType
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from backend.pinscopex.passive_rail_check import (
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_cap_farads,
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_is_ground_net,
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_is_ic_supply_pin,
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_is_nc_net,
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_is_regulator_output_pin,
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_pin_label,
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)
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from backend.pinscopex.validate import _match_constraints
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_BULK_MIN_F = 1e-6
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_HF_MAX_F = 1e-6
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_HF_MIN_F = 1e-9
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def _esl_hint(footprint: str) -> str:
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fp = (footprint or "").upper()
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if "0402" in fp:
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return "typical ESL ~0.4 nH (0402 stima)"
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if "0603" in fp:
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return "typical ESL ~0.6 nH (0603 stima)"
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if "0805" in fp:
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return "typical ESL ~0.8 nH (0805 stima)"
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return "ESL depends on package (stima)"
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def _valued_gnd_caps(graph: DesignGraph, net_name: str) -> list[tuple[str, float]]:
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out: list[tuple[str, float]] = []
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unknown = False
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for ref in graph.capacitors_on_net(net_name):
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cap = graph.components[ref]
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others = {n for n in cap.pins.values() if n != net_name}
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if not any(_is_ground_net(graph, n) for n in others):
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continue
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farads = _cap_farads(cap)
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if farads is None:
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unknown = True
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continue
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out.append((ref, farads))
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if unknown:
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return []
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return out
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def check_hf_decoupling_coverage(
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graph: DesignGraph,
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constraints_map: dict,
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) -> list[Finding]:
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findings: list[Finding] = []
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seen: set[str] = set()
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for ref, comp in sorted(graph.components.items()):
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if comp.component_type != ComponentType.IC:
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continue
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cons = _match_constraints(comp.mpn or comp.value, constraints_map)
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for pin_num, net_name in sorted(comp.pins.items(), key=lambda x: str(x[0])):
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if net_name in seen or _is_nc_net(net_name):
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continue
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is_rail = _is_ic_supply_pin(graph, cons, pin_num, net_name) or (
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_is_regulator_output_pin(cons, pin_num)
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)
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if not is_rail:
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continue
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net = graph.nets.get(net_name)
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if net and net.net_type == NetType.GROUND:
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continue
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seen.add(net_name)
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caps = _valued_gnd_caps(graph, net_name)
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if not caps:
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continue
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has_bulk = any(c >= _BULK_MIN_F for _, c in caps)
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has_hf = any(_HF_MIN_F <= c < _HF_MAX_F for _, c in caps)
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if not (has_bulk and not has_hf):
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continue
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bulk_ref = next(r for r, c in caps if c >= _BULK_MIN_F)
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fp = graph.components[bulk_ref].footprint
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pin_label = _pin_label(cons, pin_num, net_name)
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findings.append(Finding(
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designator=ref,
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mpn=comp.mpn or "",
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aspect="decoupling",
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source="hf_coverage_check",
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status="INFO",
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finding=(
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f"{ref} net '{net_name}' ({pin_label}) has bulk capacitance "
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f"but no ~100 nF ceramic for HF."
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),
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why=(
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f"Parallel Z(f) of large C is inductive above a few hundred "
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f"kHz ({_esl_hint(fp)}). Without f_sw this is not an Ω target."
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),
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recommendation=(
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f"Add a 10–100 nF ceramic from '{net_name}' to ground near "
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f"{ref}, in parallel with the bulk cap."
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),
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reference="netlist topology (stima)",
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net=net_name,
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pins=[f"{ref}.{pin_num}"],
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rule_id="PS-ESR-001",
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))
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return findings
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