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sram noise margin how can we write codes for sram cicuit

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jemmy

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sram simulation

Can anybody introduce me how to do the following 6-T SRAM bit cell analysis with Hspice:
1.Standby current on VDD;
2.Read and Write Margin;
3.bit-lin leakage

I have tried to simulate the standby current on VDD. I set BL,BL_ and WL to 0, and also using ic(Q)=1.8v(I simulate with 018u logic process model card). I find i(VDD) is very close to zero, but not a constant. Sometimes it is nagative, and sometimes it is positive number. I don't know why. I'm a beginer on SRAM and Hspice. I'm not sure whether this way is correct.

Attached pic is the sram schematic.
Thanks for your help.
 

sram hspice

usually the leakage current of MOSFET is 1E-15A \depends on Vth swing channel length and width.
so if u want to simulate 6T cell
u have to make the fitting of spice parameter for sub threshold area
if u look UCB formula sub threshold area is different behavior from satulation or non-satulation area.
if u want to simulate one 6T cell u set the option current condition less than E-15A.
from my experience the leakage current of 6T cell is difficult to simu.
so the current decade is observed.
but if u have good fitting spice paramter , u can make cell array more than a thouthand cells and u can simu using HSPICE for small error of caliculation.
 

6t sram schematic

Thanks.
Can you also introduce me something about SRAM' Static Noise Margin(SNM)?I want to know how to write Hspice input file to calculate SRAM's SNM.
 

sram spice

Please can you post Spice code?

Thanks
 
6t sram cell spice

I could find SNM by the output list file or the waveform. I don't know how one could do it separately, like displaying SNM=180mV for example. Could any body help us on this.
 
sram cell hspice code

Hello,

Please can any of you tell me the method to simulate the butterfly curve of the SRAM using Hspice and Avanwaves?? I was able to produce one side of the butterfly (the VTC of an inverter) but i cant seem to get the other side :cry:
Please any help is greatly appreciated.
 
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