diff --git a/src/lay/lay/doc/manual/lvs_symm_nodes.png b/src/lay/lay/doc/manual/lvs_symm_nodes.png
new file mode 100644
index 000000000..faf82bdf3
Binary files /dev/null and b/src/lay/lay/doc/manual/lvs_symm_nodes.png differ
diff --git a/src/lay/lay/doc/manual/lvs_tweaks.xml b/src/lay/lay/doc/manual/lvs_tweaks.xml
index f0300a18d..2e631f677 100644
--- a/src/lay/lay/doc/manual/lvs_tweaks.xml
+++ b/src/lay/lay/doc/manual/lvs_tweaks.xml
@@ -175,6 +175,52 @@ schematic.blank_circuit("CIRCUIT_NAME")
sets a flag (
+ Sometimes it is possible to omit connections in the layout because these + will not carry any current. This might simplify the layout and allow denser + packing, but finally there is a mismatch between schematic and layout. + In general, connections can be omitted if they would connect symmetric + nodes. When symmetric nodes are swapped, the circuit will not change. + Hence they will always carry the same potential (at least in theory) + and a connection between them will not carry any current. So it can + be omitted. +
+ ++ The following picture describes such a situation known as "split gate configuration". + In this case, the N1 and N2 are identical: swapping them will not change the circuit's + topology. Hence, they will carry the same potential and the red connection is not required physically. + But without such a connection, the parallel transistors (top pair and bottom pair) will not be recognized + as parallel and the pairs will not be joined into one each: +
+ +
+
+
+ KLayout provides a feature which will add such connections after extraction + of the netlist: +
+ +join_symmetric_nets("NAND2")
+
+ + This function will analyze the circuit "NAND2" in the extracted netlist and connect all symmetric + nodes within it. If this function is called before "combine_devices" (e.g. through + "netlist.simplify"), this connection is already present then and parallel devices + will be recognized and combined. +
+ ++ The argument to "join_symmetric_nets" is a glob-style pattern. "*" will analyze and + modify all circuits, but at the price of potentially introducing unwanted connections. + Hence the recommendation is to use this feature on circuits which are known to + need it. +
+
diff --git a/src/lay/lay/layHelpResources.qrc b/src/lay/lay/layHelpResources.qrc
index 34dbc7efd..d6ba81d93 100644
--- a/src/lay/lay/layHelpResources.qrc
+++ b/src/lay/lay/layHelpResources.qrc
@@ -181,6 +181,7 @@