# See LICENSE for licensing information. # # Copyright (c) 2016-2019 Regents of the University of California and The Board # of Regents for the Oklahoma Agricultural and Mechanical College # (acting for and on behalf of Oklahoma State University) # All rights reserved. # import debug from bitcell_base_array import bitcell_base_array from tech import drc, spice from globals import OPTS from sram_factory import factory class bitcell_array(bitcell_base_array): """ Creates a rows x cols array of memory cells. Assumes bit-lines and word lines are connected by abutment. """ def __init__(self, rows, cols, column_offset=0, name=""): super().__init__(rows=rows, cols=cols, column_offset=column_offset, name=name) debug.info(1, "Creating {0} {1} x {2}".format(self.name, rows, cols)) self.add_comment("rows: {0} cols: {1}".format(rows, cols)) # This will create a default set of bitline/wordline names self.create_all_bitline_names() self.create_all_wordline_names() self.create_netlist() if not OPTS.netlist_only: self.create_layout() # We don't offset this because we need to align # the replica bitcell in the control logic # self.offset_all_coordinates() def create_netlist(self): """ Create and connect the netlist """ self.add_modules() self.add_pins() self.create_instances() def create_layout(self): self.place_array("bit_r{0}_c{1}") self.add_layout_pins() self.add_boundary() self.DRC_LVS() def add_modules(self): """ Add the modules used in this design """ self.cell = factory.create(module_type=OPTS.bitcell) self.add_mod(self.cell) def create_instances(self): """ Create the module instances used in this design """ self.cell_inst = {} for col in range(self.column_size): for row in range(self.row_size): name = "bit_r{0}_c{1}".format(row, col) self.cell_inst[row, col]=self.add_inst(name=name, mod=self.cell) self.connect_inst(self.get_bitcell_pins(row, col)) def analytical_power(self, corner, load): """Power of Bitcell array and bitline in nW.""" # Dynamic Power from Bitline bl_wire = self.gen_bl_wire() cell_load = 2 * bl_wire.return_input_cap() bl_swing = OPTS.rbl_delay_percentage freq = spice["default_event_frequency"] bitline_dynamic = self.calc_dynamic_power(corner, cell_load, freq, swing=bl_swing) # Calculate the bitcell power which currently only includes leakage cell_power = self.cell.analytical_power(corner, load) # Leakage power grows with entire array and bitlines. total_power = self.return_power(cell_power.dynamic + bitline_dynamic * self.column_size, cell_power.leakage * self.column_size * self.row_size) return total_power def gen_wl_wire(self): if OPTS.netlist_only: width = 0 else: width = self.width wl_wire = self.generate_rc_net(int(self.column_size), width, drc("minwidth_m1")) # 2 access tx gate per cell wl_wire.wire_c = 2 * spice["min_tx_gate_c"] + wl_wire.wire_c return wl_wire def gen_bl_wire(self): if OPTS.netlist_only: height = 0 else: height = self.height bl_pos = 0 bl_wire = self.generate_rc_net(int(self.row_size - bl_pos), height, drc("minwidth_m1")) # 1 access tx d/s per cell bl_wire.wire_c =spice["min_tx_drain_c"] + bl_wire.wire_c return bl_wire def graph_exclude_bits(self, targ_row=None, targ_col=None): """ Excludes bits in column from being added to graph except target """ # Function is not robust with column mux configurations for row in range(self.row_size): for col in range(self.column_size): if row == targ_row and col == targ_col: continue self.graph_inst_exclude.add(self.cell_inst[row, col]) def get_cell_name(self, inst_name, row, col): """Gets the spice name of the target bitcell.""" return inst_name + '.x' + self.cell_inst[row, col].name, self.cell_inst[row, col]