sram noise margin how can we write codes for sram cicuit

[jemmy]

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.

 

[ptoo30]

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.

 

[jemmy]

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.

 

[vimalvlsi]

sram spice

Please can you post Spice code?

Thanks

 

[pvvikas]

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.

 

[fby01]

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
Please any help is greatly appreciated.