This is an analysis mode that finds the DC small signal transfer function of a node voltage or branch current due to small variations of an independent source.
Syntax: .TF V(<node>[, <ref>]) <source>
.TF I(<voltage source>) <source>
Examples:
.TF V(out) Vin
.TF V(5,3) Vin
.TF I(Vload) Vin