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Effective length of capacitance in less than or equal to zero (Cadence Spectre) (Read 2202 times)
Estimulo
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Effective length of capacitance in less than or equal to zero (Cadence Spectre)
Oct 29th, 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
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« Last Edit: Oct 29th, 2016, 3:15am by Estimulo »  

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Geoffrey_Coram
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Re: Effective length of capacitance in less than or equal to zero (Cadence Spectre)
Reply #1 - Oct 31st, 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.
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Abhi_iitm
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Re: Effective length of capacitance in less than or equal to zero (Cadence Spectre)
Reply #2 - Jun 2nd, 2018, 5:27am
 
Hey i am facing the exact same issue with the same library ,
could someone please help?
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Abhi_iitm
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Re: Effective length of capacitance in less than or equal to zero (Cadence Spectre)
Reply #3 - Jun 2nd, 2018, 5:28am
 
Geoffrey_Coram wrote on Oct 31st, 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.


I am facing the same issue though i am using the pdk for the same library
kindly help,
Regards
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Andrew Beckett
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Re: Effective length of capacitance in less than or equal to zero (Cadence Spectre)
Reply #4 - Jun 2nd, 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.
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Abhi_iitm
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Re: Effective length of capacitance in less than or equal to zero (Cadence Spectre)
Reply #5 - Jun 2nd, 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
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Geoffrey_Coram
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Re: Effective length of capacitance in less than or equal to zero (Cadence Spectre)
Reply #6 - Jun 4th, 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.)
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If at first you do succeed, STOP, raise your standards, and stop wasting your time.
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