"""ESD protection device generators for sky130.
Provides ESD NMOS pcell that matches the ESD-optimised geometry with
a large gate width, multi-finger layout, and the areaidesd marker layer.
"""
import gdsfactory as gf
from sky130.layers import LAYER
from sky130.pcells.mosfets import _add_guard_ring, _mosfet_core, _rect
[docs]
@gf.cell
def sky130_fd_pr__esd_nfet_01v8(
gate_width: float = 20.0,
gate_length: float = 0.15,
sd_width: float = 0.28,
nf: int = 4,
guard_ring: bool = True,
end_cap: float = 0.13,
) -> gf.Component:
"""ESD protection 1.8V NMOS (sky130_fd_pr__esd_nfet_01v8).
Large multi-finger NMOS optimised for ESD current handling. Geometry
follows the standard sky130 MOSFET construction but adds the ``areaidesd``
(81, 19) marker layer over the entire device area.
Args:
gate_width: transistor width (um); large default (20 um) for ESD.
gate_length: gate poly length (um) in the direction of current flow.
sd_width: source/drain contact region width (um).
nf: number of gate fingers; default 4 for ESD current spreading.
guard_ring: if True, add a pwell (P+ substrate) guard ring.
end_cap: poly extension beyond diffusion edge (um).
"""
c = gf.Component()
info = _mosfet_core(c, gate_width, gate_length, nf, is_pmos=False)
dhx = info["diff_half_x"]
hw = info["hw"]
enc = info["implant_enc"]
# ---- areaidesd marker layer ----
_rect(c, LAYER.areaidesd, -(dhx + enc), -(hw + enc), dhx + enc, hw + enc)
# ---- Guard ring ----
if guard_ring:
_add_guard_ring(c, info, is_pmos=False)
# ---- Ports ----
sd = info["sd_centers_x"]
gpc = info["gate_to_polycont"]
c.add_port(
name="GATE",
center=(info["gate_centers_x"][0], 0.0),
width=gate_width,
orientation=0,
layer=LAYER.polydrawing,
port_type="electrical",
)
c.add_port(
name="SOURCE",
center=(sd[-1], 0.0),
width=gate_width,
orientation=0,
layer=LAYER.li1drawing,
port_type="electrical",
)
c.add_port(
name="DRAIN",
center=(sd[0], 0.0),
width=gate_width,
orientation=180,
layer=LAYER.li1drawing,
port_type="electrical",
)
c.add_port(
name="BODY",
center=(0.0, -(hw + gpc)),
width=gate_width,
orientation=270,
layer=LAYER.li1drawing,
port_type="electrical",
)
return c
if __name__ == "__main__":
c = sky130_fd_pr__esd_nfet_01v8()
c.show()
