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Simulators >> Circuit Simulators >> Effective length of capacitance in less than or equal to zero (Cadence Spectre)
https://designers-guide.org/forum/YaBB.pl?num=1477728027

Message started by Estimulo on Oct 29^th, 2016, 1:00am

Title: Effective length of capacitance in less than or equal to zero (Cadence Spectre)
Post by Estimulo on Oct 29^th, 2016, 1:00am

Hello Everyone,

While simulating a design of 3:8 decoder, spectre is producing an error as :

Error found by spectre during initial setup.
ERROR (CMI-2215): I0.I6.I0.M1: The effective length of capacitance is less than or equal to zero.

I have tried changing width of M1 and transistors present in instances I0 and I6.

Please tell me, how can it be resolved.

Thanks

Title: Re: Effective length of capacitance in less than or equal to zero (Cadence Spectre)
Post by Geoffrey_Coram on Oct 31^st, 2016, 10:47am

I think there's something wrong with your setup. You shouldn't be getting those warnings about "'nf' is not a valid parameter"

I wonder if you're using a netlist from one PDK with a model library from another PDK.

Title: Re: Effective length of capacitance in less than or equal to zero (Cadence Spectre)
Post by Abhi_iitm on Jun 2^nd, 2018, 5:27am

Hey i am facing the exact same issue with the same library ,
could someone please help?

Title: Re: Effective length of capacitance in less than or equal to zero (Cadence Spectre)
Post by Abhi_iitm on Jun 2^nd, 2018, 5:28am

Geoffrey_Coram wrote on Oct 31^st, 2016, 10:47am:

I am facing the same issue though i am using the pdk for the same library
kindly help,
Regards

Title: Re: Effective length of capacitance in less than or equal to zero (Cadence Spectre)
Post by Andrew Beckett on Jun 2^nd, 2018, 6:45am

It would help somewhat if you said which PDK (and models) you were using - info such as the foundry, process node, and ideally any version number for the PDK or model files.

That will significantly increase the chance of somebody being able to help you.

Regards,

Andrew.

Title: Re: Effective length of capacitance in less than or equal to zero (Cadence Spectre)
Post by Abhi_iitm on Jun 2^nd, 2018, 6:57am

it is UMC_18_CMOS

These are the directory details indicating exact model:
G-9FD-MIXED_MODE_RFCMOS18-1.8V_3.3V-1P6M-MMC_ \
UM180FDKMFC00000OA-FDK-Ver.A02_PB \
/UM180FDKMFC00000OA_A02_DESIGNKIT \
/UM180FDKMFC00000OA_A02_PB/UMC_18_CMOS

Title: Re: Effective length of capacitance in less than or equal to zero (Cadence Spectre)
Post by Geoffrey_Coram on Jun 4^th, 2018, 7:11am

Is "n_18_mm" a mismatch model? If you look in the model files, can you determine if it is a subckt or model card? If you use regular (not mismatch) models, does the simulation work?

(You probably should not post the actual model files, since this is UMC's IP and it would likely violate an NDA.)