Coverage for klayout_pex/klayout/netlist_expander.py: 97%
70 statements
« prev ^ index » next coverage.py v7.6.9, created at 2024-12-17 17:24 +0000
1#
2# --------------------------------------------------------------------------------
3# SPDX-FileCopyrightText: 2024 Martin Jan Köhler and Harald Pretl
4# Johannes Kepler University, Institute for Integrated Circuits.
5#
6# This file is part of KPEX
7# (see https://github.com/martinjankoehler/klayout-pex).
8#
9# This program is free software: you can redistribute it and/or modify
10# it under the terms of the GNU General Public License as published by
11# the Free Software Foundation, either version 3 of the License, or
12# (at your option) any later version.
13#
14# This program is distributed in the hope that it will be useful,
15# but WITHOUT ANY WARRANTY; without even the implied warranty of
16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17# GNU General Public License for more details.
18#
19# You should have received a copy of the GNU General Public License
20# along with this program. If not, see <http://www.gnu.org/licenses/>.
21# SPDX-License-Identifier: GPL-3.0-or-later
22# --------------------------------------------------------------------------------
23#
24from __future__ import annotations
26import re
27from typing import *
29import klayout.db as kdb
31from ..log import (
32 info,
33 warning,
34)
35from ..common.capacitance_matrix import CapacitanceMatrix
38class NetlistExpander:
39 @staticmethod
40 def expand(extracted_netlist: kdb.Netlist,
41 top_cell_name: str,
42 cap_matrix: CapacitanceMatrix,
43 blackbox_devices: bool) -> kdb.Netlist:
44 expanded_netlist: kdb.Netlist = extracted_netlist.dup()
45 top_circuit: kdb.Circuit = expanded_netlist.circuit_by_name(top_cell_name)
47 if not blackbox_devices:
48 for d in top_circuit.each_device():
49 name = d.name or d.expanded_name()
50 info(f"Removing whiteboxed device {name}")
51 top_circuit.remove_device(d)
53 # create capacitor class
54 cap = kdb.DeviceClassCapacitor()
55 cap.name = 'PEX_CAP'
56 cap.description = "Extracted by kpex/FasterCap PEX"
57 expanded_netlist.add(cap)
59 fc_gnd_net = top_circuit.create_net('FC_GND') # create GROUND net
60 vsubs_net = top_circuit.create_net("VSUBS")
61 nets: List[kdb.Net] = []
63 # build table: name -> net
64 name2net: Dict[str, kdb.Net] = {n.expanded_name(): n for n in top_circuit.each_net()}
66 # find nets for the matrix axes
67 pattern = re.compile(r'^g\d+_(.*)$')
68 for idx, nn in enumerate(cap_matrix.conductor_names):
69 m = pattern.match(nn)
70 nn = m.group(1)
71 if nn not in name2net:
72 raise Exception(f"No net found with name {nn}, net names are: {list(name2net.keys())}")
73 n = name2net[nn]
74 nets.append(n)
76 cap_threshold = 0.0
78 def add_parasitic_cap(i: int,
79 j: int,
80 net1: kdb.Net,
81 net2: kdb.Net,
82 cap_value: float):
83 if cap_value > cap_threshold:
84 c: kdb.Device = top_circuit.create_device(cap, f"Cext_{i}_{j}")
85 c.connect_terminal('A', net1)
86 c.connect_terminal('B', net2)
87 c.set_parameter('C', cap_value)
88 if net1 == net2:
89 raise Exception(f"Invalid attempt to create cap {c.name} between "
90 f"same net {net1} with value {'%.12g' % cap_value}")
91 else:
92 warning(f"Ignoring capacitance matrix cell [{i},{j}], "
93 f"{'%.12g' % cap_value} is below threshold {'%.12g' % cap_threshold}")
95 # -------------------------------------------------------------
96 # Example capacitance matrix:
97 # [C11+C12+C13 -C12 -C13]
98 # [-C21 C21+C22+C23 -C23]
99 # [-C31 -C32 C31+C32+C33]
100 # -------------------------------------------------------------
101 #
102 # - Diagonal elements m[i][i] contain the capacitance over GND (Cii),
103 # but in a sum including all the other values of the row
104 #
105 # https://www.fastfieldsolvers.com/Papers/The_Maxwell_Capacitance_Matrix_WP110301_R03.pdf
106 #
107 for i in range(0, cap_matrix.dimension):
108 row = cap_matrix[i]
109 cap_ii = row[i]
110 for j in range(0, cap_matrix.dimension):
111 if i == j:
112 continue
113 cap_value = -row[j] # off-diagonals are always stored as negative values
114 cap_ii -= cap_value # subtract summands to filter out Cii
115 if j > i:
116 add_parasitic_cap(i=i, j=j,
117 net1=nets[i], net2=nets[j],
118 cap_value=cap_value)
119 if i > 0:
120 add_parasitic_cap(i=i, j=i,
121 net1=nets[i], net2=nets[0],
122 cap_value=cap_ii)
124 # Short VSUBS and FC_GND together
125 # VSUBS ... substrate block
126 # FC_GND ... FasterCap's GND, i.e. the diagonal Cii elements
127 # create capacitor class
129 res = kdb.DeviceClassResistor()
130 res.name = 'PEX_RES'
131 res.description = "Extracted by kpex/FasterCap PEX"
132 expanded_netlist.add(res)
134 gnd_net = name2net.get('GND', None)
135 if not gnd_net:
136 gnd_net = top_circuit.create_net('GND') # create GROUND net
138 c: kdb.Device = top_circuit.create_device(res, f"Rext_FC_GND_GND")
139 c.connect_terminal('A', fc_gnd_net)
140 c.connect_terminal('B', gnd_net)
141 c.set_parameter('R', 0)
143 c: kdb.Device = top_circuit.create_device(res, f"Rext_VSUBS_GND")
144 c.connect_terminal('A', vsubs_net)
145 c.connect_terminal('B', gnd_net)
146 c.set_parameter('R', 0)
148 return expanded_netlist