Probing Signals for the Parasitic Backannotation Flow

Spectre FX supports probing of subnodes and instance pins on an RC net. It is not recommended to do it for all RC nets in a big DSPF file because it may cause a huge number of signals to be saved and a big waveform file to be generated.

To enable this feature, you need to set the following two backannotation options

sfx_ba_probe_node: Specifies how to probe the nodes in an RC NET that can be set based on RC NET with wildcards supported. Possible values are rep, pin, all, gate, and primary_gate. The default value is rep.
sfx_ba_probe_node_name: Specifies how to specify the signal name. Possible values are brief and full. The default value is brief.

Wildcards are supported in both the .probe statement and the sfx_ba_probe_node option. You can limit the scope of the final signals saved using either method.

The following example probes all the nodes in the RC Net section of the DSPF file and display the full name for them.

.probe v(x1.mid)
.option sfx_ba_probe_node=all
.option sfx_ba_probe_node_name=full

Here, the pre-layout signal v(x1.mid) is specified, therefore, the probed signals are limited to it.

Finally, all the nodes in RC NET corresponding to the pre-layout node x1.mid are probed. The signal list is shown below.

Spectre FX Circuit Simulator User Guide
Product Version 23.1, September 2023