Spice Library device cannot process nested subcircuits

[tomhajjar]

Spice library is "confused" trying to "process" VCO_MOS_sub.cir. It doesn't like the three subcircuits in the middle.

Subcircuit .subckt ro_vco
sub 1
sub 2
sub 3
.ends ro_vco

Spice netlist gets processed by ngspice which works.

PLL_XSPICE_prj.zip

[ra3xdh]

The netlist contains the nested subcircuits. This syntax was not allowed by Ngspice in the past and Ngspice showed a warning and even may fail the simulation with the convergence error. Has something changed in the recent versions?

[tomhajjar]

Unsure when ngspice allowed nested sub-circuits. The vco subcircuit "vco_sub.cir" has been in the ngspice XSPICE examples folder for a VERY long time. It is so old it was replaced by "vco_sub_new.cir' and hasn't been used for many releases of ngspice. It's actually an "orphan" subcircuit that was left in the folder. "vco_sub_new.cir' uses the ngspice "exclusive" "d_osc" function. I would need to ask Holger when nested sub-circuits were allowed.

C:\Ngspice-43+_64\examples\xspice\pll

Turns out "d_osc" has a bug which explains why it's been driving me crazy... ;-)
https://sourceforge.net/p/ngspice/discussion/120973/thread/d7eb851b6c/

[tomhajjar]

@ra3xdh

I downloaded ngspice 25 from 2013 and the "vco_sub.cir" dated 2012 is identical and still has nested subcircuits...

[ra3xdh]

Fixed by #1211