mirror of https://github.com/VLSIDA/OpenRAM.git
367 lines
16 KiB
Python
367 lines
16 KiB
Python
# See LICENSE for licensing information.
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#
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# Copyright (c) 2016-2019 Regents of the University of California
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# All rights reserved.
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#
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import debug
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import design
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from tech import drc, 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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import logical_effort
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import bitcell_array
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import replica_column
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import dummy_array
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class replica_bitcell_array(design.design):
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"""
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Creates a bitcell arrow of cols x rows and then adds the replica and dummy columns
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and rows for one or two read ports. Replica columns are on the left and right, respectively.
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Dummy are the outside columns/rows with WL and BL tied to gnd.
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Requires a regular bitcell array, replica bitcell, and dummy bitcell (Bl/BR disconnected).
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"""
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def __init__(self, cols, rows, name):
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design.design.__init__(self, name)
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debug.info(1, "Creating {0} {1} x {2}".format(self.name, rows, cols))
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self.add_comment("rows: {0} cols: {1}".format(rows, cols))
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self.column_size = cols
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self.row_size = rows
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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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# We don't offset this because we need to align
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# the replica bitcell in the control logic
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#self.offset_all_coordinates()
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def create_netlist(self):
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""" Create and connect the netlist """
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self.add_modules()
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self.add_pins()
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self.create_instances()
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def add_modules(self):
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""" Array and dummy/replica columns
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d or D = dummy cell (caps to distinguish grouping)
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r or R = replica cell (caps to distinguish grouping)
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b or B = bitcell
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replica columns 1
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v v
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bdDDDDDDDDDDDDDDdb <- Dummy row
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bdDDDDDDDDDDDDDDrb <- Dummy row
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br--------------rb
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br| Array |rb
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br| row x col |rb
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br--------------rb
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brDDDDDDDDDDDDDDdb <- Dummy row
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bdDDDDDDDDDDDDDDdb <- Dummy row
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^^^^^^^^^^^^^^^
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dummy rows cols x 1
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^ dummy columns ^
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1 x (rows + 4)
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"""
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# Bitcell for port names only
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self.cell = factory.create(module_type="bitcell")
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# Bitcell array
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self.bitcell_array = factory.create(module_type="bitcell_array",
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cols=self.column_size,
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rows=self.row_size)
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self.add_mod(self.bitcell_array)
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# Replica bitline
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self.replica_column = factory.create(module_type="replica_column",
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rows=self.row_size + 4)
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self.add_mod(self.replica_column)
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# Dummy row
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self.dummy_row = factory.create(module_type="dummy_array",
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rows=1,
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cols=self.column_size)
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self.add_mod(self.dummy_row)
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# Dummy col
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self.dummy_col = factory.create(module_type="dummy_array",
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cols=1,
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rows=self.row_size + 4)
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self.add_mod(self.dummy_col)
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def add_pins(self):
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self.wl_names = [x for x in self.bitcell_array.pins if x.startswith("w")]
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self.bl_names = [x for x in self.bitcell_array.pins if x.startswith("b")]
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# top/bottom rows (in the middle)
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self.replica_wl_names = ["replica_"+x for x in self.cell.pins if x.startswith("w")]
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self.dummy_wl_names = ["dummy_"+x for x in self.cell.pins if x.startswith("w")]
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self.dummy_bl_names = ["dummy_"+x for x in self.cell.pins if x.startswith("b")]
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self.dummy_row_bl_names = self.bl_names
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# dummy row and replica on each side of the bitcell rows
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self.replica_col_wl_names = [x+"_0" for x in self.dummy_wl_names] \
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+ ["replica_"+x+"_0" for x in self.cell.list_all_wl_names()] \
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+ self.wl_names \
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+ ["replica_"+x+"_1" for x in self.cell.list_all_wl_names()] \
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+ [x+"_1" for x in self.dummy_wl_names]
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self.replica_bl_names = ["replica_"+x for x in self.cell.pins if x.startswith("b")]
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# left/right rows
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self.dummy_col_wl_names = self.replica_col_wl_names
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self.add_pin_list(self.bl_names)
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self.add_pin_list([x+"_0" for x in self.replica_bl_names])
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self.add_pin_list([x+"_1" for x in self.replica_bl_names])
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self.add_pin_list([x for x in self.replica_col_wl_names if not x.startswith("dummy")])
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self.add_pin("vdd")
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self.add_pin("gnd")
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def create_instances(self):
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""" Create the module instances used in this design """
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supplies = ["vdd", "gnd"]
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# Main array
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self.bitcell_array_inst=self.add_inst(name="bitcell_array",
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mod=self.bitcell_array)
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self.connect_inst(self.bitcell_array.pins)
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# Replica columns (two even if one port for now)
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self.replica_col_left_inst=self.add_inst(name="replica_col_left",
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mod=self.replica_column)
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self.connect_inst([x+"_0" for x in self.replica_bl_names] + self.replica_col_wl_names + supplies)
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self.replica_col_right_inst=self.add_inst(name="replica_col_right",
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mod=self.replica_column)
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self.connect_inst([x+"_1" for x in self.replica_bl_names] + self.replica_col_wl_names[::-1] + supplies)
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# Replica rows with replica bitcell
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self.dummy_row_bottop_inst=self.add_inst(name="dummy_row_bottop",
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mod=self.dummy_row)
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self.connect_inst(self.dummy_row_bl_names + [x+"_0" for x in self.replica_wl_names] + supplies)
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self.dummy_row_topbot_inst=self.add_inst(name="dummy_row_topbot",
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mod=self.dummy_row)
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self.connect_inst(self.dummy_row_bl_names + [x+"_1" for x in self.replica_wl_names] + supplies)
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# Dummy rows without replica bitcell
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self.dummy_row_botbot_inst=self.add_inst(name="dummy_row_botbot",
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mod=self.dummy_row)
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self.connect_inst(self.dummy_row_bl_names + [x+"_0" for x in self.dummy_wl_names] + supplies)
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self.dummy_row_toptop_inst=self.add_inst(name="dummy_row_toptop",
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mod=self.dummy_row)
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self.connect_inst(self.dummy_row_bl_names + [x+"_1" for x in self.dummy_wl_names] + supplies)
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# Dummy columns
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self.dummy_col_left_inst=self.add_inst(name="dummy_col_left",
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mod=self.dummy_col)
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self.connect_inst([x+"_0" for x in self.dummy_bl_names] + self.dummy_col_wl_names + supplies)
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self.dummy_col_right_inst=self.add_inst(name="dummy_col_right",
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mod=self.dummy_col)
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self.connect_inst([x+"_1" for x in self.dummy_bl_names] + self.dummy_col_wl_names + supplies)
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def create_layout(self):
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self.height = (self.row_size+4)*self.dummy_row.height
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self.width = (self.column_size+4)*self.replica_column.width
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# This is a bitcell x bitcell offset to scale
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offset = vector(self.replica_column.width, self.dummy_row.height)
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self.bitcell_array_inst.place(offset=[0,0])
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self.replica_col_left_inst.place(offset=offset.scale(-1,-2))
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self.replica_col_right_inst.place(offset=offset.scale(0,2)+self.bitcell_array_inst.ur(),
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mirror="MX")
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self.dummy_row_toptop_inst.place(offset=offset.scale(0,2)+self.bitcell_array_inst.ul(),
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mirror="MX")
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self.dummy_row_topbot_inst.place(offset=offset.scale(0,0)+self.bitcell_array_inst.ul())
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self.dummy_row_bottop_inst.place(offset=offset.scale(0,0),
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mirror="MX")
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self.dummy_row_botbot_inst.place(offset=offset.scale(0,-2))
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self.dummy_col_left_inst.place(offset=offset.scale(-2,-2))
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self.dummy_col_right_inst.place(offset=offset.scale(1,-2)+self.bitcell_array_inst.lr())
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self.translate_all(offset.scale(-2,-2))
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self.add_layout_pins()
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self.add_boundary()
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self.DRC_LVS()
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def add_layout_pins(self):
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""" Add the layout pins """
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# Main array wl and bl/br
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pin_names = self.bitcell_array.get_pin_names()
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for pin_name in pin_names:
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if pin_name.startswith("wl"):
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pin_list = self.bitcell_array_inst.get_pins(pin_name)
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for pin in pin_list:
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self.add_layout_pin_rect_center(text=pin_name,
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layer=pin.layer,
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offset=pin.center(),
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width=self.width,
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height=pin.height())
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elif pin_name.startswith("bl") or pin_name.startswith("br"):
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pin_list = self.bitcell_array_inst.get_pins(pin_name)
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for pin in pin_list:
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self.add_layout_pin_rect_center(text=pin_name,
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layer=pin.layer,
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offset=pin.center(),
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width=pin.width(),
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height=self.height)
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for index,(side1,side2) in enumerate([("bottop","left"),("topbot","right")]):
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inst = getattr(self, "dummy_row_{}_inst".format(side1))
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pin_names = inst.mod.get_pin_names()
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for pin_name in pin_names:
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if pin_name.startswith("wl"):
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pin_list = inst.get_pins(pin_name)
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for pin in pin_list:
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name = "replica_{0}_{1}".format(pin_name,index)
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self.add_layout_pin_rect_center(text=name,
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layer=pin.layer,
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offset=pin.center(),
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width=self.width,
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height=pin.height())
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# Replica columns
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for index,side in enumerate(["left","right"]):
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inst = getattr(self, "replica_col_{}_inst".format(side))
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pin_names = inst.mod.get_pin_names()
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for pin_name in pin_names:
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if pin_name.startswith("bl") or pin_name.startswith("br"):
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pin_list = inst.get_pins(pin_name)
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for pin in pin_list:
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name = "replica_{0}_{1}".format(pin_name,index)
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self.add_layout_pin(text=name,
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layer=pin.layer,
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offset=pin.ll().scale(1,0),
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width=pin.width(),
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height=self.height)
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for pin_name in ["vdd","gnd"]:
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for inst in [self.bitcell_array_inst,
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self.replica_col_left_inst, self.replica_col_right_inst,
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self.dummy_col_left_inst, self.dummy_col_right_inst,
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self.dummy_row_toptop_inst, self.dummy_row_topbot_inst,
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self.dummy_row_bottop_inst, self.dummy_row_botbot_inst]:
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pin_list = inst.get_pins(pin_name)
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for pin in pin_list:
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self.add_power_pin(name=pin_name, loc=pin.center(), vertical=True, start_layer=pin.layer)
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# Non-pins
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for side in ["botbot", "toptop"]:
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inst = getattr(self, "dummy_row_{}_inst".format(side))
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pin_names = inst.mod.get_pin_names()
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for pin_name in pin_names:
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if pin_name.startswith("wl"):
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pin_list = inst.get_pins(pin_name)
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for pin in pin_list:
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self.add_rect_center(layer=pin.layer,
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offset=pin.center(),
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width=self.width,
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height=pin.height())
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for side in ["left", "right"]:
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inst = getattr(self, "dummy_col_{}_inst".format(side))
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pin_names = inst.mod.get_pin_names()
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for pin_name in pin_names:
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if pin_name.startswith("b"):
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pin_list = inst.get_pins(pin_name)
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for pin in pin_list:
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self.add_rect_center(layer=pin.layer,
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offset=pin.center(),
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width=pin.width(),
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height=self.height)
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def analytical_delay(self, corner, slew, load):
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"""Returns relative delay of the bitline in the bitcell array"""
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from tech import parameter
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#The load being driven/drained is mostly the bitline but could include the sense amp or the column mux.
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#The load from the bitlines is due to the drain capacitances from all the other bitlines and wire parasitics.
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drain_load = logical_effort.convert_farad_to_relative_c(parameter['bitcell_drain_cap'])
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wire_unit_load = .05 * drain_load #Wires add 5% to this.
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bitline_load = (drain_load+wire_unit_load)*self.row_size
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return [self.cell.analytical_delay(corner, slew, load+bitline_load)]
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def analytical_power(self, corner, load):
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"""Power of Bitcell array and bitline in nW."""
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from tech import drc, parameter
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# Dynamic Power from Bitline
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bl_wire = self.gen_bl_wire()
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cell_load = 2 * bl_wire.return_input_cap()
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bl_swing = parameter["rbl_height_percentage"]
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freq = spice["default_event_rate"]
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bitline_dynamic = self.calc_dynamic_power(corner, cell_load, freq, swing=bl_swing)
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#Calculate the bitcell power which currently only includes leakage
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cell_power = self.cell.analytical_power(corner, load)
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#Leakage power grows with entire array and bitlines.
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total_power = self.return_power(cell_power.dynamic + bitline_dynamic * self.column_size,
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cell_power.leakage * self.column_size * self.row_size)
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return total_power
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def gen_wl_wire(self):
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if OPTS.netlist_only:
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width = 0
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else:
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width = self.width
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wl_wire = self.generate_rc_net(int(self.column_size), width, drc("minwidth_metal1"))
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wl_wire.wire_c = 2*spice["min_tx_gate_c"] + wl_wire.wire_c # 2 access tx gate per cell
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return wl_wire
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def gen_bl_wire(self):
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if OPTS.netlist_only:
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height = 0
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else:
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height = self.height
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bl_pos = 0
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bl_wire = self.generate_rc_net(int(self.row_size-bl_pos), height, drc("minwidth_metal1"))
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bl_wire.wire_c =spice["min_tx_drain_c"] + bl_wire.wire_c # 1 access tx d/s per cell
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return bl_wire
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def output_load(self, bl_pos=0):
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bl_wire = self.gen_bl_wire()
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return bl_wire.wire_c # sense amp only need to charge small portion of the bl
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# set as one segment for now
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def input_load(self):
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wl_wire = self.gen_wl_wire()
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return wl_wire.return_input_cap()
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def get_wordline_cin(self):
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"""Get the relative input capacitance from the wordline connections in all the bitcell"""
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#A single wordline is connected to all the bitcells in a single row meaning the capacitance depends on the # of columns
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bitcell_wl_cin = self.cell.get_wl_cin()
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total_cin = bitcell_wl_cin * self.column_size
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return total_cin
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