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Different Parameters between exported CDL netlist and spectre SCS netlist

Yizhou

Hi, all!

I'm using Virtuoso 23.10.030 and met a problem when use netlist file for simulation. I have used two different ways to generate netlist file according to How to export spice netlist? - Custom IC SKILL - Cadence Technology Forums - Cadence Community.

When I'm exporting CDL netlist file with SI command (or equivalently, File - Export - CDL) and all default settings, I get a FET subcircuit like this:

XN0 gnd! gnd! gnd! gnd! gnd! slvtnfet_mmw_5t m=8 w=10u l=20n nf=8 nrep=1
+ p_la=0 ngcon=2 ulp=0 lle_pcpc=188n dist_nrep=-1.0 pre_layout_rf_beol_local=5
+ swrfmhc_local=-1.0 swhpmhc_local=-1.0

When I'm exporting spectre SCS netlist with createNetlist( ?recreateAll t), I get the same FET subcircuit like this:

N0 (0 0 0 0 0) slvtnfet_mmw_5t w=10u l=20n m=8 as=1.175p ad=940f ps=14.38u \
pd=11.504u nf=8 par=(8) par_nf=(8) * (1) plorient=0 acv_opt=-1 \
ptwell=0 ngcon=2 nscon=1 ndcon=1 p_la=0 p_wa=0 ulp=0 lle_pcpc=188n \
lle_sa=406n lle_sb=406n lle_rxrxa=208n lle_rxrxb=208n \
lle_rxrxn=210n lle_rxrxs=210n lle_pcrxn=160n lle_pcrxs=160n \
w_tie_v=2 w_tie_h=2 pre_layout_rf_beol_local=5 swrfmhc_local=-1 \
swhpmhc_local=-1 nrep=1 dist_nrep=-1

Apparently, SCS netlist contains more parameters than CDL netlist. When I simulate them respectively (not in this testbench, but a more complex one), the results are significantly different. After I add same parameter in SCS netlist to CDL netlist (converted to CDL format, the results become same. It indicates that CDL netlist misses some parameters during exporting.

In this case, I wonder if there anything I need to set when exporting CDL netlist so that I can get all parameters?

Best,

Yizhou

  • Andrew Beckett

    Yizhou,

    Why would you expect them to be the same? CDL netlists are intended for physical verification not simulation. Consequently, the CDL netlist would normally only contain relevant parameters that can be physically verified by an LVS rule deck, and not include things that are for simulation only. The CDF for the device would normally list which parameters get netlisted for spectre and which parameters get netlisted for auCdl, and I wouldn't expect them to be the same. 

    Andrew

  • Yizhou
    in reply to Andrew Beckett

    Andrew,

    Thank you very much for your answer. I'm curious about this because I have previously built a automatic simulation workflow with CDL netlist simulation (use simulator lang=spice). But that PDK is much simpler (without many parameters like this), so the results are the same between CDL netlist simulation and those with ADE (maestro). This time when I move to a new PDK it causes a problem.

    According to your answer, I would move my whole workflow to Spectre SCS netlist.

    Thank you again!

    Yizhou

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