import design import debug from tech import drc, parameter, spice from vector import vector import contact from math import ceil from ptx import ptx from globals import OPTS class pbitcell(design.design): """ This module implements a parametrically sized multi-port bitcell. """ def __init__(self): name = "pbitcell" design.design.__init__(self, name) debug.info(2, "create a multi-port bitcell") self.num_write = 2 self.num_read = 2 self.create_layout() self.DRC_LVS() def add_pins(self): self.add_pin("WROW") self.add_pin("WBL") self.add_pin("WBL_bar") for k in range(0,self.num_read): self.add_pin("RROW{}".format(k)) self.add_pin("RBL{}".format(k)) self.add_pin("RBL_bar{}".format(k)) self.add_pin("vdd") self.add_pin("gnd") def create_layout(self): self.create_ptx() self.add_storage() self.add_rails() self.add_write_transistors() self.add_read_transistors() self.extend_well() #self.add_fail() def create_ptx(self): """ Create ptx all transistors. Also define measurements to be used throughout bitcell. """ self.i_nmos = ptx(width=2.3*parameter["min_tx_size"], tx_type="nmos", connect_active=True, connect_poly=True) self.add_mod(self.i_nmos) self.i_pmos = ptx(width=parameter["min_tx_size"], tx_type="pmos", connect_active=True, connect_poly=True) self.add_mod(self.i_pmos) # create ptx for write transitors self.w_nmos = ptx(width=1.5*parameter["min_tx_size"], tx_type="nmos", connect_active=True, connect_poly=True) self.add_mod(self.w_nmos) # create ptx for read transistors self.r_nmos = ptx(width=parameter["min_tx_size"], tx_type="nmos", connect_active=True, connect_poly=True) self.add_mod(self.r_nmos) # determine metal contact extentions self.in_ex = 0.5*(self.i_nmos.active_contact.height - self.i_nmos.active_height) self.ip_ex = 0.5*(self.i_pmos.active_contact.height - self.i_pmos.active_height) self.w_ex = 0.5*(self.w_nmos.active_contact.height - self.w_nmos.active_height) self.r_ex = 0.5*(self.r_nmos.active_contact.height - self.r_nmos.active_height) # determine global measurements spacer = 5*drc["minwidth_metal2"] + self.w_ex + self.r_ex self.w_tile_width = 3*parameter["min_tx_size"] + self.w_nmos.active_height self.r_tile_width = 3*parameter["min_tx_size"] + self.r_nmos.active_height self.inv_gap = 5*contact.poly.width self.leftmost_xpos = -(self.i_nmos.active_width + 1.5*parameter["min_tx_size"] + drc["well_enclosure_active"]) \ - self.num_write*(3*parameter["min_tx_size"] + self.w_nmos.active_height) \ - (self.num_read-1)*(3*parameter["min_tx_size"] + self.r_nmos.active_height) - spacer - self.r_nmos.active_height self.botmost_ypos = -2*drc["minwidth_metal1"] - self.num_write*2*drc["minwidth_metal2"] - self.num_read*2*drc["minwidth_metal2"] self.topmost_ypos = self.inv_gap + self.i_nmos.active_height + self.i_pmos.active_height + drc["poly_extend_active"] + 2*drc["minwidth_metal1"] self.cell_width = -2*self.leftmost_xpos self.cell_height = self.topmost_ypos - self.botmost_ypos def add_rails(self): """ Adds rails for vdd and gnd. """ self.gnd_position = vector(self.leftmost_xpos, -2*drc["minwidth_metal1"]) self.gnd = self.add_layout_pin(text="gnd", layer="metal1", offset=self.gnd_position, width=self.cell_width, height=drc["minwidth_metal1"]) self.vdd_position = vector(self.leftmost_xpos, self.i_pmosL.get_pin("S").uc().y + drc["minwidth_metal1"]) self.vdd = self.add_layout_pin(text="vdd", layer="metal1", offset=self.vdd_position, width=self.cell_width, height=drc["minwidth_metal1"]) # connect sources to rails # connect nmos to gnd i_nmosL_source = self.i_nmosL.get_pin("S").bc() gnd_posL = vector(self.i_nmosL.get_pin("S").bc().x, self.gnd_position.y + drc["minwidth_metal1"]) self.add_path("metal1", [i_nmosL_source, gnd_posL]) i_nmosR_drain = self.i_nmosR.get_pin("D").bc() gnd_posR = vector(self.i_nmosR.get_pin("D").bc().x, self.gnd_position.y + drc["minwidth_metal1"]) self.add_path("metal1", [i_nmosR_drain, gnd_posR]) # connect pmos to vdd i_pmosL_source = self.i_pmosL.get_pin("S").uc() vdd_posL = vector(self.i_nmosL.get_pin("S").uc().x, self.vdd_position.y) self.add_path("metal1", [i_pmosL_source, vdd_posL]) i_pmosR_drain = self.i_pmosR.get_pin("D").uc() vdd_posR = vector(self.i_nmosR.get_pin("D").uc().x, self.vdd_position.y) self.add_path("metal1", [i_pmosR_drain, vdd_posR]) def add_storage(self): """ Creates the crossed coupled inverters that act as storage for the bitcell. """ # calculate offsets lit_xpos = -(self.i_nmos.active_width + 1.5*parameter["min_tx_size"]) rit_xpos = 1.5*parameter["min_tx_size"] it_ypos = self.inv_gap + self.i_nmos.active_height # create active self.i_nmosL = self.add_inst(name="i_nmosL", mod=self.i_nmos, offset=[lit_xpos,0]) self.connect_inst(["IR", "IL", "gnd", "gnd"]) self.i_nmosR = self.add_inst(name="i_nmosR", mod=self.i_nmos, offset=[rit_xpos,0]) self.connect_inst(["IL", "IR", "gnd", "gnd"]) self.i_pmosL = self.add_inst(name="i_pmosL", mod=self.i_pmos, offset=[lit_xpos, it_ypos]) self.connect_inst(["IL", "IR", "vdd", "vdd"]) self.i_pmosR = self.add_inst(name="i_pmosR", mod=self.i_pmos, offset=[rit_xpos, it_ypos]) self.connect_inst(["IL", "IR", "vdd", "vdd"]) # connect poly for inverters i_nmosL_poly = self.i_nmosL.get_pin("G").uc() i_pmosL_poly = self.i_pmosL.get_pin("G").bc() self.add_path("poly", [i_nmosL_poly, i_pmosL_poly]) i_nmosR_poly = self.i_nmosR.get_pin("G").uc() i_pmosR_poly = self.i_pmosR.get_pin("G").bc() self.add_path("poly", [i_nmosR_poly, i_pmosR_poly]) # connect drains for inverters i_nmosL_drain = self.i_nmosL.get_pin("D").uc() i_pmosL_drain = self.i_pmosL.get_pin("D").bc() self.add_path("metal1", [i_nmosL_drain, i_pmosL_drain]) i_nmosR_source = self.i_nmosR.get_pin("S").uc() i_pmosR_source = self.i_pmosR.get_pin("S").bc() self.add_path("metal1", [i_nmosR_source, i_pmosR_source]) # add cross couple vias offset = vector(self.i_nmosL.get_pin("D").ur().x + contact.poly.height, self.i_nmos.active_height + 0.6*self.inv_gap) self.icl = self.add_contact(layers=("poly", "contact", "metal1"), offset=offset, rotate=90) offset = vector(self.i_nmosR.get_pin("S").ul().x, self.i_nmos.active_height + 0.2*self.inv_gap) self.icr = self.add_contact(layers=("poly", "contact", "metal1"), offset=offset, rotate=90) # connect vias to poly (cross couple) correct = 0.5*(self.i_nmos.active_contact.width - drc["minwidth_metal1"]) cross_width = 0.5*self.i_nmos.active_width - 0.5*drc["minwidth_poly"] + 3*parameter["min_tx_size"] + correct offset = vector(self.i_nmosL.get_pin("G").ur().x, self.i_nmos.active_height + 0.2*self.inv_gap) self.add_rect(layer="poly", offset=offset, width=cross_width, height=contact.poly.width) offset = vector(self.i_nmosL.get_pin("D").ur().x, self.i_nmos.active_height + 0.6*self.inv_gap) self.add_rect(layer="poly", offset=offset, width=cross_width, height=contact.poly.width) def add_write_transistors(self): """ Define variables relevant to write transistors """ lit_xpos = -(self.i_nmos.active_width + 1.5*parameter["min_tx_size"]) rit_xpos = 1.5*parameter["min_tx_size"] rot_correct = self.w_nmos.active_height self.w_nmosL = [None] * self.num_write self.w_nmosR = [None] * self.num_write self.wrow_positions = [None] * self.num_write self.wbl_positions = [None] * self.num_write self.wbl_bar_positions = [None] * self.num_write for k in range(0,self.num_write): """ Add transistors and WROW lines """ wrow_ypos = -2*drc["minwidth_metal1"] - (k+1)*2*drc["minwidth_metal2"] lwt_xpos = lit_xpos + rot_correct - (k+1)*self.w_tile_width rwt_xpos = rit_xpos + self.i_nmos.active_width + 3*parameter["min_tx_size"] + rot_correct + k*self.w_tile_width self.w_nmosL[k] = self.add_inst(name="w_nmosL{}".format(k), mod=self.w_nmos, offset=[lwt_xpos,0], rotate=90) self.connect_inst(["IR", "WROW{}".format(k), "WBL{}".format(k), "gnd"]) self.w_nmosR[k] = self.add_inst(name="w_nmosR{}".format(k), mod=self.w_nmos, offset=[rwt_xpos,0], rotate=90) self.connect_inst(["IL", "WROW{}".format(k), "WBL_bar{}".format(k), "gnd"]) # add WROW lines self.wrow_positions[k] = vector(self.leftmost_xpos, wrow_ypos) self.add_layout_pin(text="WROW{}".format(k), layer="metal1", offset=self.wrow_positions[k], width=self.cell_width, height=drc["minwidth_metal1"]) """ Source/WBL/WBL_bar connections """ # connect sources to WBL and WBL_bar self.wbl_positions[k] = vector(lwt_xpos - drc["minwidth_metal2"],self.botmost_ypos) self.add_layout_pin(text="WBL{}".format(k), layer="metal2", offset=self.wbl_positions[k], width=drc["minwidth_metal2"], height=self.cell_height) self.wbl_bar_positions[k] = vector(rwt_xpos - rot_correct,self.botmost_ypos) self.add_layout_pin(text="WBL_bar{}".format(k), layer="metal2", offset=self.wbl_bar_positions[k], width=drc["minwidth_metal2"], height=self.cell_height) # add vias to connect source of wt to WBL and WBL_bar offset = self.w_nmosL[k].get_pin("S").ll() + vector(self.w_nmos.active_height, 0) self.add_contact(layers=("metal1", "via1", "metal2"), offset=offset, rotate=90) offset = self.w_nmosR[k].get_pin("S").ll() + vector(self.w_nmos.active_height, 0) self.add_contact(layers=("metal1", "via1", "metal2"), offset=offset, rotate=90) """ Gate/WROW connections """ # add vias to connect wt gate to WROW correct = vector(0.5*(drc["minwidth_metal2"] - drc["minwidth_metal1"]),0) offset = self.w_nmosL[k].get_pin("S").ll() - vector(drc["minwidth_metal2"] + contact.poly.width, 0) self.add_contact(layers=("poly", "contact", "metal1"), offset=offset) self.add_contact(layers=("metal1", "via1", "metal2"), offset=offset+correct) via_offsetL = offset + vector(0.5*contact.poly.width, 0) gate_offsetL = vector(offset.x + 0.5*contact.poly.width, self.w_nmosL[k].get_pin("G").ul().y) self.add_path("poly", [via_offsetL, gate_offsetL], width=contact.poly.width) self.add_path("poly", [gate_offsetL, self.w_nmosL[k].get_pin("G").lc()]) offset = self.w_nmosR[k].get_pin("S").lr() + vector(drc["minwidth_metal2"], 0) self.add_contact(layers=("poly", "contact", "metal1"), offset=offset) self.add_contact(layers=("metal1", "via1", "metal2"), offset=offset+correct) via_offsetR = offset + vector(0.5*contact.poly.width, 0) gate_offsetR = vector(offset.x + 0.5*contact.poly.width, self.w_nmosR[k].get_pin("G").ur().y) self.add_path("poly", [via_offsetR, gate_offsetR], width=contact.poly.width) self.add_path("poly", [gate_offsetR, self.w_nmosR[k].get_pin("G").rc()]) # add vias to WROW lines offset = vector(via_offsetL.x + contact.m1m2.height - 0.5*drc["minwidth_metal2"],self.wrow_positions[k].y) self.add_contact(layers=("metal1", "via1", "metal2"), offset=offset, rotate=90) wrow_offset = vector(via_offsetL.x, self.wrow_positions[k].y) self.add_path("metal2", [via_offsetL, wrow_offset]) offset = vector(via_offsetR.x + 0.5*drc["minwidth_metal2"], self.wrow_positions[k].y) self.add_contact(layers=("metal1", "via1", "metal2"), offset=offset, rotate=90) wrow_offset = vector(via_offsetR.x, self.wrow_positions[k].y) self.add_path("metal2", [via_offsetR, wrow_offset]) """ Drain/Storage connections """ if(k == self.num_write-1): # add vias to connect input of inverters to drain of wt offset = vector(lit_xpos - drc["minwidth_metal1"], self.i_nmos.active_height + 0.2*self.inv_gap) self.add_contact(layers=("poly", "contact", "metal1"), offset=offset, rotate=90) offset = vector(rit_xpos + self.i_nmos.active_width + drc["minwidth_metal1"] + contact.poly.height, self.i_nmos.active_height + 0.2*self.inv_gap) self.add_contact(layers=("poly", "contact", "metal1"), offset=offset, rotate=90) # connect drains of wt to input of inverters correct = 0.5*(contact.poly.width - drc["minwidth_metal1"]) w_nmosL_drain = self.w_nmosL[k].get_pin("D").rc() via_offsetLB = vector(lit_xpos - drc["minwidth_metal1"] - contact.poly.height, self.w_nmosL[k].get_pin("D").rc().y) via_offsetLT = vector(lit_xpos - drc["minwidth_metal1"] - contact.poly.height, self.i_nmos.active_height + 0.2*self.inv_gap + contact.poly.width - correct) self.add_path("metal1", [w_nmosL_drain, via_offsetLB, via_offsetLT]) w_nmosR_drain = self.w_nmosR[k].get_pin("D").lc() via_offsetRB = vector(rit_xpos + self.i_nmos.active_width + drc["minwidth_metal1"] + contact.poly.height, self.w_nmosR[k].get_pin("D").lc().y) via_offsetRT = vector(rit_xpos + self.i_nmos.active_width + drc["minwidth_metal1"] + contact.poly.height, self.i_nmos.active_height + 0.2*self.inv_gap + contact.poly.width - correct) self.add_path("metal1", [w_nmosR_drain, via_offsetRB, via_offsetRT]) via_offsetL = vector(lit_xpos - drc["minwidth_metal1"] - contact.poly.height, self.i_nmos.active_height + 0.2*self.inv_gap + 0.5*contact.poly.width) gate_offsetL = vector(self.i_nmosL.get_pin("G").ll().x, self.i_nmos.active_height + 0.2*self.inv_gap + 0.5*contact.poly.width) self.add_path("poly", [via_offsetL, gate_offsetL], width=contact.poly.width) via_offsetR = vector(rit_xpos + self.i_nmos.active_width + drc["minwidth_metal1"] + contact.poly.height, self.i_nmos.active_height + 0.2*self.inv_gap + 0.5*contact.poly.width) gate_offsetR = vector(self.i_nmosR.get_pin("G").lr().x, self.i_nmos.active_height + 0.2*self.inv_gap + 0.5*contact.poly.width) self.add_path("poly", [via_offsetR, gate_offsetR], width=contact.poly.width) def add_read_transistors(self): """ Define variables relevant to read transistors """ lit_xpos = -(self.i_nmos.active_width + 1.5*parameter["min_tx_size"]) rit_xpos = 1.5*parameter["min_tx_size"] wrow_ypos = -2*drc["minwidth_metal1"] - self.num_write*2*drc["minwidth_metal2"] lwt_xpos = lit_xpos - self.num_write*self.w_tile_width rwt_xpos = rit_xpos + self.i_nmos.active_width + self.num_write*self.w_tile_width rot_correct = self.r_nmos.active_height spacer = 5*drc["minwidth_metal2"] self.r_nmosL = [None] * self.num_read self.r_nmosR = [None] * self.num_read self.rrow_positions = [None] * self.num_read self.rbl_positions = [None] * self.num_read self.rbl_bar_positions = [None] * self.num_read for k in range(0,self.num_read): """ Add transistors and RROW lines """ lrt_xpos = lwt_xpos - spacer - self.r_nmos.active_height + rot_correct - k*self.r_tile_width rrt_xpos = rwt_xpos + spacer + rot_correct + k*self.r_tile_width self.r_nmosL[k] = self.add_inst(name="r_nmosL", mod=self.r_nmos, offset=[lrt_xpos,0], rotate=90) self.connect_inst(["RROW{}".format(k), "IL", "RBL{}".format(k), "gnd"]) self.r_nmosR[k] = self.add_inst(name="r_nmosR", mod=self.r_nmos, offset=[rrt_xpos,0], rotate=90) self.connect_inst(["RROW{}".format(k), "IR", "RBL_bar{}".format(k), "gnd"]) # add RROW lines rrow_ypos = wrow_ypos - (k+1)*2*drc["minwidth_metal2"] self.rrow_positions[k] = vector(self.leftmost_xpos, rrow_ypos) self.add_layout_pin(text="RROW{}".format(k), layer="metal1", offset=self.rrow_positions[k], width=self.cell_width, height=drc["minwidth_metal1"]) """ Drain/RBL/RBL_bar connections """ # connect drains to RBL and RBL_bar self.rbl_positions[k] = vector(self.r_nmosL[k].get_pin("D").rc().x + drc["minwidth_metal2"],self.botmost_ypos) self.add_layout_pin(text="RBL{}".format(k), layer="metal2", offset=self.rbl_positions[k], width=drc["minwidth_metal2"], height=self.cell_height) self.rbl_bar_positions[k] = vector(self.r_nmosR[k].get_pin("D").lc().x - 2*drc["minwidth_metal2"],self.botmost_ypos) self.add_layout_pin(text="RBL_bar{}".format(k), layer="metal2", offset=self.rbl_bar_positions[k], width=drc["minwidth_metal2"], height=self.cell_height) # add vias to connect drain of rt to RBL and RBL_bar offset = self.r_nmosL[k].get_pin("D").ll() + vector(contact.m1m2.height, 0) self.add_contact(layers=("metal1", "via1", "metal2"), offset=offset, rotate=90) offset = self.r_nmosR[k].get_pin("D").ll() + vector(contact.m1m2.height, 0) self.add_contact(layers=("metal1", "via1", "metal2"), offset=offset, rotate=90) # connect drain of rt to RBL and RBL_bar rbl_offset = vector(self.rbl_positions[k].x, self.r_nmosL[k].get_pin("D").lc().y) self.add_path("metal2", [self.r_nmosL[k].get_pin("D").lc(), rbl_offset]) rbl_bar_offset = vector(self.rbl_bar_positions[k].x, self.r_nmosR[k].get_pin("D").rc().y) self.add_path("metal2", [self.r_nmosR[k].get_pin("D").rc(), rbl_bar_offset]) """ Source/RROW connections """ # add vias on rt sources offset = self.r_nmosL[k].get_pin("S").ll() + vector(contact.m1m2.height, 0) self.add_contact(layers=("metal1", "via1", "metal2"), offset=offset, rotate=90) offset = self.r_nmosR[k].get_pin("S").ll() + vector(contact.m1m2.height, 0) self.add_contact(layers=("metal1", "via1", "metal2"), offset=offset, rotate=90) # add vias on rrows offset = vector(self.r_nmosL[k].get_pin("S").ll().x + contact.m1m2.height, self.rrow_positions[k].y) self.add_contact(layers=("metal1", "via1", "metal2"), offset=offset, rotate=90) offset = vector(self.r_nmosR[k].get_pin("S").ll().x + contact.m1m2.height, self.rrow_positions[k].y) self.add_contact(layers=("metal1", "via1", "metal2"), offset=offset, rotate=90) # connect sources of rt to rrows rrow_offset = vector(self.r_nmosL[k].get_pin("S").bc().x, self.rrow_positions[k].y) self.add_path("metal2", [self.r_nmosL[k].get_pin("S").bc(), rrow_offset]) rrow_offset = vector(self.r_nmosR[k].get_pin("S").bc().x, self.rrow_positions[k].y) self.add_path("metal2", [self.r_nmosR[k].get_pin("S").bc(), rrow_offset]) """ Gate/inverter connections """ # add vias to connect to gate of rt offsetL = vector(self.r_nmosL[k].get_pin("D").lr().x + drc["minwidth_metal1"], self.r_nmosL[k].get_pin("G").lr().y) self.add_contact(layers=("poly", "contact", "metal1"), offset=offsetL) offsetR = vector(self.r_nmosR[k].get_pin("D").ll().x - drc["minwidth_metal1"] - contact.poly.width, self.r_nmosR[k].get_pin("G").ll().y) self.add_contact(layers=("poly", "contact", "metal1"), offset=offsetR) # add metal1 path between gate vias and inverter inputs midL = vector(offsetL.x + 0.5*contact.poly.width, self.i_nmos.active_height + 0.6*self.inv_gap + 0.5*drc["minwidth_metal1"]) gate_offsetL = vector(self.i_nmosL.get_pin("D").ll().x, self.i_nmos.active_height + 0.6*self.inv_gap + 0.5*drc["minwidth_metal1"]) self.add_path("metal1", [offsetL+vector(0.5*contact.poly.width,0), midL, gate_offsetL]) midR = vector(offsetR.x + 0.5*contact.poly.width, self.i_nmos.active_height + 0.6*self.inv_gap + 0.5*drc["minwidth_metal1"]) gate_offsetR = vector(self.i_nmosR.get_pin("S").lr().x, self.i_nmos.active_height + 0.6*self.inv_gap + 0.5*drc["minwidth_metal1"]) self.add_path("metal1", [offsetR+vector(0.5*contact.poly.width,0), midR, gate_offsetR]) def extend_well(self): offset = vector(self.leftmost_xpos, -2*drc["minwidth_metal1"]) well_height = self.w_nmos.well_width + 2*drc["minwidth_metal1"] self.add_rect(layer="pwell", offset=offset, width=self.cell_width, height=well_height) lit_xpos = -(self.i_nmos.active_width + 1.5*parameter["min_tx_size"] + drc["well_enclosure_active"]) it_ypos = self.inv_gap + self.i_nmos.active_height - drc["well_enclosure_active"] offset = [lit_xpos,it_ypos] well_width = 2*self.i_pmos.active_width + 3*parameter["min_tx_size"] + 2*drc["well_enclosure_active"] well_height = self.i_pmos.well_height + 2*drc["minwidth_metal1"] self.add_rect(layer="nwell", offset=offset, width=well_width, height=well_height) def add_fail(self): # for failing drc frail_width = self.well_width = 10*drc["minwidth_tx"] frail_height = self.rail_height = drc["minwidth_metal1"] self.gnd_position = vector(-25*drc["minwidth_tx"], - 1.5 * drc["minwidth_metal1"] - 0.5 * frail_height) # for tiling purposes self.add_layout_pin(text="gnd", layer="metal1", offset=self.gnd_position, width=frail_width, height=frail_height) self.gnd_position2 = vector(-25*drc["minwidth_tx"], - 0.5 * drc["minwidth_metal1"]) self.add_layout_pin(text="gnd2", layer="metal1", offset=self.gnd_position2, width=frail_width, height=frail_height)