# 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 contact import design import debug from tech import layer from vector import vector from globals import OPTS class pgate(design.design): """ This is a module that implements some shared functions for parameterized gates. """ def __init__(self, name, height=None): """ Creates a generic cell """ design.design.__init__(self, name) if height: self.height = height elif not height: # By default, we make it 10 M1 pitch tall self.height = 10*self.m1_pitch self.create_netlist() if not OPTS.netlist_only: self.create_layout() self.add_boundary() self.DRC_LVS() def create_netlist(self): """ Pure virtual function """ debug.error("Must over-ride create_netlist.", -1) def create_layout(self): """ Pure virtual function """ debug.error("Must over-ride create_layout.", -1) def connect_pin_to_rail(self, inst, pin, supply): """ Connects a ptx pin to a supply rail. """ source_pin = inst.get_pin(pin) supply_pin = self.get_pin(supply) if supply_pin.overlaps(source_pin): return if supply == "gnd": height = supply_pin.by() - source_pin.by() elif supply == "vdd": height = supply_pin.uy() - source_pin.by() else: debug.error("Invalid supply name.", -1) if abs(height) > 0: self.add_rect(layer="m1", offset=source_pin.ll(), height=height, width=source_pin.width()) def route_input_gate(self, pmos_inst, nmos_inst, ypos, name, position="left"): """ Route the input gate to the left side of the cell for access. Position specifies to place the contact the left, center, or right of gate. """ nmos_gate_pin = nmos_inst.get_pin("G") pmos_gate_pin = pmos_inst.get_pin("G") # Check if the gates are aligned and give an error if they aren't! if nmos_gate_pin.ll().x != pmos_gate_pin.ll().x: self.gds_write("unaliged_gates.gds") debug.check(nmos_gate_pin.ll().x == pmos_gate_pin.ll().x, "Connecting unaligned gates not supported. See unaligned_gates.gds.") # Pick point on the left of NMOS and up to PMOS nmos_gate_pos = nmos_gate_pin.ul() + vector(0.5 * self.poly_width, 0) pmos_gate_pos = vector(nmos_gate_pos.x, pmos_gate_pin.bc().y) self.add_path("poly", [nmos_gate_pos, pmos_gate_pos]) # Add the via to the cell midpoint along the gate left_gate_offset = vector(nmos_gate_pin.lx(), ypos) # Center is completely symmetric. contact_width = contact.poly_contact.width contact_m1_width = contact.poly_contact.second_layer_width contact_m1_height = contact.poly_contact.second_layer_height if position == "center": contact_offset = left_gate_offset \ + vector(0.5 * self.poly_width, 0) elif position == "farleft": contact_offset = left_gate_offset \ - vector(0.5 * contact.poly_contact.width, 0) elif position == "left": contact_offset = left_gate_offset \ - vector(0.5 * contact_width - 0.5 * self.poly_width, 0) elif position == "right": contact_offset = left_gate_offset \ + vector(0.5 * contact_width + 0.5 * self.poly_width, 0) else: debug.error("Invalid contact placement option.", -1) v=self.add_via_center(layers=self.poly_stack, offset=contact_offset) self.add_layout_pin_rect_center(text=name, layer="m1", offset=contact_offset, width=contact_m1_width, height=contact_m1_height) # This is to ensure that the contact is # connected to the gate mid_point = contact_offset.scale(0.5, 1) \ + left_gate_offset.scale(0.5, 0) self.add_rect_center(layer="poly", offset=mid_point, height=contact.poly_contact.first_layer_width, width=left_gate_offset.x - contact_offset.x) def extend_wells(self): """ Extend the n/p wells to cover whole cell """ # This should match the cells in the cell library nwell_y_offset = 0.48 * self.height full_height = self.height + 0.5*self.m1_width # FIXME: float rounding problem if "nwell" in layer: # Add a rail width to extend the well to the top of the rail nwell_max_offset = max(self.find_highest_layer_coords("nwell").y, full_height) nwell_position = vector(0, nwell_y_offset) - vector(self.well_extend_active, 0) nwell_height = nwell_max_offset - nwell_y_offset self.add_rect(layer="nwell", offset=nwell_position, width=self.well_width, height=nwell_height) if "vtg" in layer: self.add_rect(layer="vtg", offset=nwell_position, width=self.well_width, height=nwell_height) # Start this half a rail width below the cell if "pwell" in layer: pwell_min_offset = min(self.find_lowest_layer_coords("pwell").y, -0.5 * self.m1_width) pwell_position = vector(-self.well_extend_active, pwell_min_offset) pwell_height = nwell_y_offset - pwell_position.y self.add_rect(layer="pwell", offset=pwell_position, width=self.well_width, height=pwell_height) if "vtg" in layer: self.add_rect(layer="vtg", offset=pwell_position, width=self.well_width, height=pwell_height) def add_nwell_contact(self, pmos, pmos_pos): """ Add an nwell contact next to the given pmos device. """ layer_stack = self.active_stack # To the right a spacing away from the pmos right active edge contact_xoffset = pmos_pos.x + pmos.active_width \ + self.active_space # Must be at least an well enclosure of active down # from the top of the well # OR align the active with the top of PMOS active. max_y_offset = self.height + 0.5 * self.m1_width contact_yoffset = min(pmos_pos.y + pmos.active_height - pmos.active_contact.first_layer_height, max_y_offset - pmos.active_contact.first_layer_height / 2 - self.nwell_enclose_active) contact_offset = vector(contact_xoffset, contact_yoffset) # Offset by half a contact in x and y contact_offset += vector(0.5 * pmos.active_contact.first_layer_width, 0.5 * pmos.active_contact.first_layer_height) self.nwell_contact = self.add_via_center(layers=layer_stack, offset=contact_offset, implant_type="n", well_type="n") self.add_rect_center(layer="m1", offset=contact_offset + vector(0, 0.5 * (self.height-contact_offset.y)), width=self.nwell_contact.mod.second_layer_width, height=self.height - contact_offset.y) # Now add the full active and implant for the PMOS # active_offset = pmos_pos + vector(pmos.active_width,0) # This might be needed if the spacing between the actives # is not satisifed # self.add_rect(layer="active", # offset=active_offset, # width=pmos.active_contact.width, # height=pmos.active_height) # we need to ensure implants don't overlap and are # spaced far enough apart # implant_spacing = self.implant_space+self.implant_enclose_active # implant_offset = active_offset + vector(implant_spacing,0) \ # - vector(0,self.implant_enclose_active) # implant_width = pmos.active_contact.width \ # + 2*self.implant_enclose_active # implant_height = pmos.active_height + 2*self.implant_enclose_active # self.add_rect(layer="nimplant", # offset=implant_offset, # width=implant_width, # height=implant_height) # Return the top of the well def add_pwell_contact(self, nmos, nmos_pos): """ Add an pwell contact next to the given nmos device. """ layer_stack = self.active_stack pwell_position = vector(0, -0.5 * self.m1_width) # To the right a spacing away from the nmos right active edge contact_xoffset = nmos_pos.x + nmos.active_width \ + self.active_space # Must be at least an well enclosure of active up # from the bottom of the well contact_yoffset = max(nmos_pos.y, self.nwell_enclose_active \ - nmos.active_contact.first_layer_height / 2) contact_offset = vector(contact_xoffset, contact_yoffset) # Offset by half a contact contact_offset += vector(0.5 * nmos.active_contact.first_layer_width, 0.5 * nmos.active_contact.first_layer_height) self.pwell_contact= self.add_via_center(layers=layer_stack, offset=contact_offset, implant_type="p", well_type="p") self.add_rect_center(layer="m1", offset=contact_offset.scale(1,0.5), width=self.pwell_contact.mod.second_layer_width, height=contact_offset.y) # Now add the full active and implant for the NMOS # active_offset = nmos_pos + vector(nmos.active_width,0) # This might be needed if the spacing between the actives # is not satisifed # self.add_rect(layer="active", # offset=active_offset, # width=nmos.active_contact.width, # height=nmos.active_height) # implant_spacing = self.implant_space+self.implant_enclose_active # implant_offset = active_offset + vector(implant_spacing,0) \ # - vector(0,self.implant_enclose_active) # implant_width = nmos.active_contact.width \ # + 2*self.implant_enclose_active # implant_height = nmos.active_height + 2*self.implant_enclose_active # self.add_rect(layer="pimplant", # offset=implant_offset, # width=implant_width, # height=implant_height) def determine_width(self): """ Determine the width based on the well contacts (assumed to be on the right side) """ # Width is determined by well contact and spacing self.width = max(self.nwell_contact.rx(), self.pwell_contact.rx()) + self.m1_space self.well_width = self.width + 2 * self.nwell_enclose_active # Height is an input parameter, so it is not recomputed.