mirror of https://github.com/VLSIDA/OpenRAM.git
227 lines
10 KiB
Python
227 lines
10 KiB
Python
import contact
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import design
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import debug
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from tech import drc, parameter, spice
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from vector import vector
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from globals import OPTS
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from sram_factory import factory
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class pgate(design.design):
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"""
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This is a module that implements some shared functions for parameterized gates.
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"""
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def __init__(self, name, height=None):
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""" Creates a generic cell """
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design.design.__init__(self, name)
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if height:
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self.height = height
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elif not height:
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b = factory.create(module_type="bitcell")
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self.height = b.height
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def connect_pin_to_rail(self,inst,pin,supply):
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""" Connects a ptx pin to a supply rail. """
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source_pin = inst.get_pin(pin)
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supply_pin = self.get_pin(supply)
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if supply_pin.overlaps(source_pin):
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return
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if supply=="gnd":
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height=supply_pin.by()-source_pin.by()
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elif supply=="vdd":
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height=supply_pin.uy()-source_pin.by()
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else:
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debug.error("Invalid supply name.",-1)
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if abs(height)>0:
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self.add_rect(layer="metal1",
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offset=source_pin.ll(),
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height=height,
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width=source_pin.width())
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def route_input_gate(self, pmos_inst, nmos_inst, ypos, name, position="left", rotate=False):
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""" Route the input gate to the left side of the cell for access.
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Position specifies to place the contact the left, center, or right of gate. """
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nmos_gate_pin = nmos_inst.get_pin("G")
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pmos_gate_pin = pmos_inst.get_pin("G")
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# Check if the gates are aligned and give an error if they aren't!
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debug.check(nmos_gate_pin.ll().x==pmos_gate_pin.ll().x, "Connecting unaligned gates not supported.")
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# Pick point on the left of NMOS and connect down to PMOS
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nmos_gate_pos = nmos_gate_pin.ll() + vector(0.5*self.poly_width,0)
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pmos_gate_pos = vector(nmos_gate_pos.x,pmos_gate_pin.bc().y)
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self.add_path("poly",[nmos_gate_pos,pmos_gate_pos])
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# Add the via to the cell midpoint along the gate
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left_gate_offset = vector(nmos_gate_pin.lx(),ypos)
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# Center is completely symmetric.
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if rotate:
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contact_width = contact.poly.height
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contact_m1_width = contact.poly.second_layer_height
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contact_m1_height = contact.poly.second_layer_width
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directions = ("H","V")
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else:
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contact_width = contact.poly.width
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contact_m1_width = contact.poly.second_layer_width
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contact_m1_height = contact.poly.second_layer_height
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directions = ("V","H")
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if position=="center":
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contact_offset = left_gate_offset + vector(0.5*self.poly_width, 0)
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elif position=="left":
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contact_offset = left_gate_offset - vector(0.5*contact_width - 0.5*self.poly_width, 0)
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elif position=="right":
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contact_offset = left_gate_offset + vector(0.5*contact.width + 0.5*self.poly_width, 0)
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else:
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debug.error("Invalid contact placement option.", -1)
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# Non-preferred direction via
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self.add_via_center(layers=("poly", "contact", "metal1"),
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offset=contact_offset,
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directions=directions)
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# self.add_layout_pin_segment_center(text=name,
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# layer="metal1",
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# start=left_gate_offset.scale(0,1),
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# end=left_gate_offset)
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self.add_layout_pin_rect_center(text=name,
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layer="metal1",
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offset=contact_offset,
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width=contact_m1_width,
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height=contact_m1_height)
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# This is to ensure that the contact is connected to the gate
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mid_point = contact_offset.scale(0.5,1)+left_gate_offset.scale(0.5,0)
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self.add_rect_center(layer="poly",
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offset=mid_point,
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height=contact.poly.first_layer_width,
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width=left_gate_offset.x-contact_offset.x)
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def extend_wells(self, middle_position):
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""" Extend the n/p wells to cover whole cell """
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# Add a rail width to extend the well to the top of the rail
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max_y_offset = self.height + 0.5*self.m1_width
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self.nwell_position = middle_position
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nwell_height = max_y_offset - middle_position.y
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if drc("has_nwell"):
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self.add_rect(layer="nwell",
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offset=middle_position,
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width=self.well_width,
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height=nwell_height)
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self.add_rect(layer="vtg",
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offset=self.nwell_position,
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width=self.well_width,
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height=nwell_height)
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pwell_position = vector(0,-0.5*self.m1_width)
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pwell_height = middle_position.y-pwell_position.y
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if drc("has_pwell"):
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self.add_rect(layer="pwell",
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offset=pwell_position,
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width=self.well_width,
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height=pwell_height)
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self.add_rect(layer="vtg",
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offset=pwell_position,
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width=self.well_width,
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height=pwell_height)
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def add_nwell_contact(self, pmos, pmos_pos):
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""" Add an nwell contact next to the given pmos device. """
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layer_stack = ("active", "contact", "metal1")
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# To the right a spacing away from the pmos right active edge
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contact_xoffset = pmos_pos.x + pmos.active_width + drc("active_to_body_active")
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# Must be at least an well enclosure of active down from the top of the well
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# OR align the active with the top of PMOS active.
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max_y_offset = self.height + 0.5*self.m1_width
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contact_yoffset = min(pmos_pos.y + pmos.active_height - pmos.active_contact.first_layer_height,
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max_y_offset - pmos.active_contact.first_layer_height/2 - self.well_enclose_active)
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contact_offset = vector(contact_xoffset, contact_yoffset)
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# Offset by half a contact in x and y
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contact_offset += vector(0.5*pmos.active_contact.first_layer_width,
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0.5*pmos.active_contact.first_layer_height)
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self.nwell_contact=self.add_via_center(layers=layer_stack,
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offset=contact_offset,
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directions=("H","V"),
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implant_type="n",
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well_type="n")
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self.add_rect_center(layer="metal1",
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offset=contact_offset + vector(0,0.5*(self.height-contact_offset.y)),
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width=self.nwell_contact.mod.second_layer_width,
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height=self.height - contact_offset.y)
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# Now add the full active and implant for the PMOS
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#active_offset = pmos_pos + vector(pmos.active_width,0)
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# This might be needed if the spacing between the actives is not satisifed
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# self.add_rect(layer="active",
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# offset=active_offset,
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# width=pmos.active_contact.width,
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# height=pmos.active_height)
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# we need to ensure implants don't overlap and are spaced far enough apart
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# implant_spacing = self.implant_space+self.implant_enclose_active
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# implant_offset = active_offset + vector(implant_spacing,0) - vector(0,self.implant_enclose_active)
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# implant_width = pmos.active_contact.width + 2*self.implant_enclose_active
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# implant_height = pmos.active_height + 2*self.implant_enclose_active
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# self.add_rect(layer="nimplant",
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# offset=implant_offset,
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# width=implant_width,
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# height=implant_height)
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# Return the top of the well
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def add_pwell_contact(self, nmos, nmos_pos):
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""" Add an pwell contact next to the given nmos device. """
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layer_stack = ("active", "contact", "metal1")
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pwell_position = vector(0,-0.5*self.m1_width)
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# To the right a spacing away from the nmos right active edge
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contact_xoffset = nmos_pos.x + nmos.active_width + drc("active_to_body_active")
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# Must be at least an well enclosure of active up from the bottom of the well
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contact_yoffset = max(nmos_pos.y,
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self.well_enclose_active - nmos.active_contact.first_layer_height/2)
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contact_offset = vector(contact_xoffset, contact_yoffset)
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# Offset by half a contact
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contact_offset += vector(0.5*nmos.active_contact.first_layer_width,
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0.5*nmos.active_contact.first_layer_height)
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self.pwell_contact=self.add_via_center(layers=layer_stack,
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offset=contact_offset,
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directions=("H","V"),
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implant_type="p",
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well_type="p")
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self.add_rect_center(layer="metal1",
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offset=contact_offset.scale(1,0.5),
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width=self.pwell_contact.mod.second_layer_width,
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height=contact_offset.y)
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# Now add the full active and implant for the NMOS
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# active_offset = nmos_pos + vector(nmos.active_width,0)
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# This might be needed if the spacing between the actives is not satisifed
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# self.add_rect(layer="active",
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# offset=active_offset,
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# width=nmos.active_contact.width,
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# height=nmos.active_height)
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# implant_spacing = self.implant_space+self.implant_enclose_active
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# implant_offset = active_offset + vector(implant_spacing,0) - vector(0,self.implant_enclose_active)
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# implant_width = nmos.active_contact.width + 2*self.implant_enclose_active
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# implant_height = nmos.active_height + 2*self.implant_enclose_active
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# self.add_rect(layer="pimplant",
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# offset=implant_offset,
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# width=implant_width,
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# height=implant_height)
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