Bitcell supply routing fixes.

Flatten and simplify 1rw 1r bitcell.
Move bitcell vias to M3 if rotation is limited.
Simplify replica bitcell vdd routing.

compiler/base/hierarchy_layout.py

@@ -926,22 +926,30 @@ class layout(lef.lef):
 
                 
         
-    def add_power_pin(self, name, loc, rotate=90, m1_too=True):
+    def add_power_pin(self, name, loc, rotate=90, start_layer="metal1"):
         """ 
-        Add a single power pin from M3 down to M1 at the given center location
+        Add a single power pin from M3 down to M1 at the given center location.
+        The starting layer is specified to determine which vias are needed.
         """
-        if m1_too:
+        
+        if start_layer=="metal1":
             self.add_via_center(layers=("metal1", "via1", "metal2"),
                                 offset=loc,
                                 rotate=float(rotate))
-        via=self.add_via_center(layers=("metal2", "via2", "metal3"),
+        if start_layer=="metal1" or start_layer=="metal2":
-                                offset=loc,
+            via=self.add_via_center(layers=("metal2", "via2", "metal3"),
-                                rotate=float(rotate))
+                                    offset=loc,
-        self.add_layout_pin_rect_center(text=name,
+                                    rotate=float(rotate))
-                                        layer="metal3",
+        if start_layer=="metal3":
-                                        offset=loc,
+            self.add_layout_pin_rect_center(text=name,
-                                        width=via.width,
+                                            layer="metal3",
-                                        height=via.height)
+                                            offset=loc)
+        else:
+            self.add_layout_pin_rect_center(text=name,
+                                            layer="metal3",
+                                            offset=loc,
+                                            width=via.width,
+                                            height=via.height)
         
     def add_power_ring(self, bbox):
         """

compiler/bitcells/pbitcell.py

@@ -80,7 +80,7 @@ class pbitcell(design.design):
             self.offset_all_coordinates()
             gnd_overlap = vector(0, 0.5*contact.well.width)
             self.translate_all(gnd_overlap)
-        self.DRC_LVS()
+
 
     def add_pins(self):
         """ add pins and set names for bitlines and wordlines """
@@ -323,20 +323,21 @@ class pbitcell(design.design):
         # Add rails for vdd and gnd
         gnd_ypos = self.rowline_offset - self.total_ports*self.rowline_spacing
         self.gnd_position = vector(0, gnd_ypos)
-        self.gnd = self.add_layout_pin_rect_center(text="gnd",
+        self.add_rect_center(layer="metal1",
-                                                   layer="metal1",
+                             offset=self.gnd_position,
-                                                   offset=self.gnd_position,
+                             width=self.width,
-                                                   width=self.width,
+                             height=self.m1_width)
-                                                   height=self.m1_width)
+        self.add_power_pin("gnd", vector(0,gnd_ypos))
-
+        
+        
         vdd_ypos = self.inverter_nmos_ypos + self.inverter_nmos.active_height + self.inverter_gap + self.inverter_pmos.active_height + self.vdd_offset
         self.vdd_position = vector(0, vdd_ypos)
-        self.vdd = self.add_layout_pin_rect_center(text="vdd",
+        self.add_rect_center(layer="metal1",
-                                                   layer="metal1",
+                             offset=self.vdd_position,
-                                                   offset=self.vdd_position,
+                             width=self.width,
-                                                   width=self.width,
+                             height=self.m1_width)
-                                                   height=self.m1_width)
+        self.add_power_pin("vdd", vector(0,vdd_ypos))
-
+        
     def create_readwrite_ports(self):
         """
         Creates read/write ports to the bit cell. A differential pair of transistor can both read and write, like in a 6T cell.

compiler/modules/bitcell_array.py

@@ -138,7 +138,8 @@ class bitcell_array(design.design):
                 inst = self.cell_inst[row,col]
                 for pin_name in ["vdd", "gnd"]:
                     for pin in inst.get_pins(pin_name):
-                        self.add_power_pin(pin_name, pin.center(), 0, pin.layer=="metal1")
+                        self.add_power_pin(pin_name, pin.center(), 0, pin.layer)
+                            
 
     def analytical_delay(self, slew, load=0):
         from tech import drc

compiler/modules/replica_bitline.py

@@ -265,15 +265,8 @@ class replica_bitline(design.design):
         pin = self.rbl_inv_inst.get_pin("vdd")
         self.add_power_pin("vdd", pin.lc())
             
-        # Replica bitcell needs to be routed up to M3
         pin=self.rbc_inst.get_pin("vdd")
-        # Don't rotate this via to vit in FreePDK45. In the custom cell, the pin cannot be placed
+        self.add_power_pin("vdd", pin.center(), 0, pin.layer)
-        # directly on vdd or there will be a drc error with a wordline. Place the pin slightly farther
-        # away then route to it. A better solution would be to rotate the m1 in the via or move the pin
-        # a m1_pitch below the entire cell.
-        pin_extension = pin.center() - vector(0,self.m1_pitch)
-        self.add_power_pin("vdd", pin_extension, rotate=0)
-        self.add_path("metal1", [pin.center(), pin_extension])
         
         for pin in self.rbc_inst.get_pins("gnd"):
             self.add_power_pin("gnd", pin.center())