mirror of https://github.com/VLSIDA/OpenRAM.git
optimize tx binning for area
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jcirimel
parent
5666e79287
commit
08f6bd8d24
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@ -17,22 +17,39 @@ from globals import OPTS
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if(OPTS.tech_name == "s8"):
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from tech import nmos_bins, pmos_bins, accuracy_requirement
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class pgate(design.design):
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"""
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This is a module that implements some shared
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functions for parameterized gates.
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"""
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def __init__(self, name, height=None):
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def __init__(self, name, height=None, add_wells=True):
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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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# By default, we make it 10 M1 pitch tall
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self.height = 10*self.m1_pitch
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# By default, something simple
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self.height = 14 * self.m1_pitch
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self.add_wells = add_wells
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if "li" in layer:
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self.route_layer = "li"
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else:
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self.route_layer = "m1"
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self.route_layer_width = getattr(self, "{}_width".format(self.route_layer))
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self.route_layer_space = getattr(self, "{}_space".format(self.route_layer))
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self.route_layer_pitch = getattr(self, "{}_pitch".format(self.route_layer))
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# This is the space from a S/D contact to the supply rail
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contact_to_vdd_rail_space = 0.5 * self.m1_width + self.m1_space
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# This is a poly-to-poly of a flipped cell
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poly_to_poly_gate_space = self.poly_extend_active + self.poly_space
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self.top_bottom_space = max(contact_to_vdd_rail_space,
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poly_to_poly_gate_space)
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self.create_netlist()
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if not OPTS.netlist_only:
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self.create_layout()
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@ -47,27 +64,27 @@ class pgate(design.design):
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""" Pure virtual function """
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debug.error("Must over-ride create_layout.", -1)
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def connect_pin_to_rail(self, inst, pin, supply):
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def connect_pin_to_rail(self, inst, pin_name, supply_name):
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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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supply_pin = self.get_pin(supply_name)
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if abs(height) > 0:
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self.add_rect(layer="m1",
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source_pins = inst.get_pins(pin_name)
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for source_pin in source_pins:
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if supply_name == "gnd":
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height = supply_pin.by() - source_pin.by()
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elif supply_name == "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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debug.check(supply_pin.layer == source_pin.layer, "Supply pin is not on correct layer.")
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self.add_rect(layer=source_pin.layer,
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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"):
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def route_input_gate(self, pmos_inst, nmos_inst, ypos, name, position="left", directions=None):
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"""
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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
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@ -93,8 +110,6 @@ class pgate(design.design):
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# Center is completely symmetric.
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contact_width = contact.poly_contact.width
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contact_m1_width = contact.poly_contact.second_layer_width
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contact_m1_height = contact.poly_contact.second_layer_height
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if position == "center":
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contact_offset = left_gate_offset \
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@ -111,18 +126,16 @@ class pgate(design.design):
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else:
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debug.error("Invalid contact placement option.", -1)
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if hasattr(self, "li_stack"):
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self.add_via_center(layers=self.li_stack,
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offset=contact_offset)
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self.add_via_center(layers=self.poly_stack,
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offset=contact_offset)
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via = self.add_via_stack_center(from_layer="poly",
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to_layer=self.route_layer,
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offset=contact_offset,
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directions=directions)
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self.add_layout_pin_rect_center(text=name,
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layer="m1",
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layer=self.route_layer,
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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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width=via.mod.second_layer_width,
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height=via.mod.second_layer_height)
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# This is to ensure that the contact is
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# connected to the gate
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mid_point = contact_offset.scale(0.5, 1) \
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@ -137,7 +150,7 @@ class pgate(design.design):
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# This should match the cells in the cell library
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self.nwell_y_offset = 0.48 * self.height
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full_height = self.height + 0.5* self.m1_width
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full_height = self.height + 0.5 * self.m1_width
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# FIXME: float rounding problem
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if "nwell" in layer:
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@ -148,12 +161,12 @@ class pgate(design.design):
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nwell_height = nwell_max_offset - self.nwell_y_offset
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self.add_rect(layer="nwell",
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offset=nwell_position,
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width=self.well_width,
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width=self.width + 2 * self.well_extend_active,
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height=nwell_height)
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if "vtg" in layer:
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self.add_rect(layer="vtg",
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offset=nwell_position,
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width=self.well_width,
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width=self.width + 2 * self.well_extend_active,
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height=nwell_height)
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# Start this half a rail width below the cell
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@ -164,12 +177,12 @@ class pgate(design.design):
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pwell_height = self.nwell_y_offset - pwell_position.y
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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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width=self.width + 2 * self.well_extend_active,
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height=pwell_height)
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if "vtg" in layer:
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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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width=self.width + 2 * self.well_extend_active,
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height=pwell_height)
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def add_nwell_contact(self, pmos, pmos_pos):
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@ -194,12 +207,10 @@ class pgate(design.design):
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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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implant_type="n",
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well_type="n")
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if hasattr(self, "li_stack"):
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self.add_via_center(layers=self.li_stack,
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offset=contact_offset)
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well_type="n",
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directions=("V", "V"))
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self.add_rect_center(layer="m1",
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self.add_rect_center(layer=self.route_layer,
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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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@ -249,13 +260,10 @@ class pgate(design.design):
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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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implant_type="p",
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well_type="p")
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if hasattr(self, "li_stack"):
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self.add_via_center(layers=self.li_stack,
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offset=contact_offset)
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self.add_rect_center(layer="m1",
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well_type="p",
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directions=("V", "V"))
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self.add_rect_center(layer=self.route_layer,
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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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@ -279,13 +287,33 @@ class pgate(design.design):
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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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def route_supply_rails(self):
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""" Add vdd/gnd rails to the top and bottom. """
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self.add_layout_pin_rect_center(text="gnd",
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layer=self.route_layer,
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offset=vector(0.5 * self.width, 0),
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width=self.width)
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self.add_layout_pin_rect_center(text="vdd",
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layer=self.route_layer,
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offset=vector(0.5 * self.width, self.height),
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width=self.width)
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def determine_width(self):
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""" Determine the width based on the well contacts (assumed to be on the right side) """
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# It was already set or is left as default (minimum)
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# Width is determined by well contact and spacing and allowing a supply via between each cell
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self.width = max(self.nwell_contact.rx(), self.pwell_contact.rx()) + self.m1_space + 0.5 * contact.m1_via.width
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self.well_width = self.width + 2 * self.nwell_enclose_active
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# Height is an input parameter, so it is not recomputed.
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if self.add_wells:
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width = max(self.nwell_contact.rx(), self.pwell_contact.rx()) + self.m1_space + 0.5 * contact.m1_via.width
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# Height is an input parameter, so it is not recomputed.
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else:
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max_active_xoffset = self.find_highest_layer_coords("active").x
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max_route_xoffset = self.find_highest_layer_coords(self.route_layer).x + 0.5 * self.m1_space
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width = max(max_active_xoffset, max_route_xoffset)
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self.width = width
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@staticmethod
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def bin_width(tx_type, target_width):
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@ -307,16 +335,20 @@ class pgate(design.design):
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base_bins = []
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scaled_bins = []
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scaling_factors = []
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scaled_bins.append(bins[-1])
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base_bins.append(bins[-1])
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scaling_factors.append(1)
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for width in bins[0:-1]:
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for width in bins:
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m = math.ceil(target_width / width)
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base_bins.append(width)
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scaling_factors.append(m)
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scaled_bins.append(m * width)
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select = bisect_left(scaled_bins, target_width)
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select = -1
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for i in reversed(range(0, len(scaled_bins))):
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if abs(target_width - scaled_bins[i])/target_width <= 1-accuracy_requirement:
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select = i
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break
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if select == -1:
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debug.error("failed to bin tx size {}, try reducing accuracy requirement".format(target_width), 1)
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scaling_factor = scaling_factors[select]
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scaled_bin = scaled_bins[select]
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selected_bin = base_bins[select]
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@ -346,4 +378,4 @@ class pgate(design.design):
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return(scaled_bins)
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def bin_accuracy(self, ideal_width, width):
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return abs(1-(ideal_width - width)/ideal_width)
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return abs(1-(ideal_width - width)/ideal_width)
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