Added a generator for constant bias-voltage generator.

openfasoc/generators/glayout/glayout/flow/blocks/bias_gen/__init__.py

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+from glayout.flow.blocks.bias_gen.bias_gen import bias_gen

openfasoc/generators/glayout/glayout/flow/blocks/bias_gen/bias_gen.py

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+# Primitives
+from glayout.flow.primitives.fet import pmos
+from glayout.flow.primitives.fet import nmos
+
+from glayout.flow.primitives.guardring import tapring
+
+# Standard
+from glayout.flow.pdk.mappedpdk import MappedPDK
+from glayout.flow.pdk.gf180_mapped import gf180_mapped_pdk
+from gdsfactory import Component
+
+# Utility
+from glayout.flow.pdk.util.comp_utils import evaluate_bbox, prec_center
+
+# Routing
+from glayout.flow.routing.straight_route import straight_route
+from glayout.flow.routing.c_route import c_route
+
+def bias_gen(pdk: MappedPDK):
+    # Create a top level component
+    bias_gen = Component()
+
+    # Bias Generator requires two NFETs of different thresholds. Retain dummies on east and west sides
+    nfet_M1 = nmos(pdk, with_substrate_tap=False, with_dummy=(True, True))
+    nfet_M2 = nmos(pdk, with_substrate_tap=False, with_dummy=(True, True))
+    bias_gen_M1 = bias_gen << nfet_M1
+    bias_gen_M2 = bias_gen << nfet_M2
+
+    # Relative Movement of the M1 transistor so that it doesn't overlap on M2
+    M2_dimension = evaluate_bbox(nfet_M2)
+    bias_gen_M1.movex(-M2_dimension[0]-pdk.util_max_metal_seperation())
+
+
+    # Routing 
+    ## Route the Gate from M1 to M2
+    bias_gen << straight_route(pdk, bias_gen_M1.ports["multiplier_0_gate_E"], bias_gen_M2.ports["multiplier_0_gate_W"])
+    ## Route the Drain to Gate of M2
+    bias_gen << c_route(pdk, bias_gen_M2.ports["multiplier_0_drain_E"], bias_gen_M2.ports["multiplier_0_gate_E"])
+    ## Calculate the centre of the bias_gen component so that the tapring could be centered around the component. 
+    shift_amount = -prec_center(bias_gen.flatten())[0]
+
+    tap_ring = tapring(pdk, enclosed_rectangle=evaluate_bbox(bias_gen.flatten(), padding=pdk.util_max_metal_seperation()))
+    tap_ring_ref = bias_gen << tap_ring
+    tap_ring_ref.movex(shift_amount)
+
+    return bias_gen
+
+bias_gen_component = bias_gen(gf180_mapped_pdk)
+bias_gen_component.show()
+
+# Write to GDS
+bias_gen_component.write_gds('bias_gen.gds')
+
+# Run magic DRC
+magic_drc_result = gf180_mapped_pdk.drc_magic(bias_gen_component, bias_gen_component.name)
+if magic_drc_result :
+    print("DRC is clean: ", magic_drc_result)
+else:
+    print("DRC failed. Please try again.")