monte carlo simulation for vth deviation?

[Lantis]

vth variation monte carlo simulation

Dear All:
I got some questions when I perform monte carlo simulation.
There are two transistor Mp1 and Mb2:

mp1 va va vr1 vr1 pch w=2.7u l=3u m=1 delvto='DeltaVt_MMB2'

MMB2 net25 va vdd! vdd! pch W=20.25u L=1u M=12 +delvto='DeltaVt_MMB2'
.param DeltaVt_MMB2 = agauss(0,0.01,3)

I want to let the two transistor matching so I let the delvto value the same. But when I see the vth deviation from Awaves

.probe dc vtmb2=par('LV9(x8.MMB2)') vtmp1=par('LV9(x8.mp1)')

The vth variation of these two transistor still different with each other.

what should I do if I want to simulate this matching effect?

Can any one could help me?

 

[bear7679]

delvto

What is the voltage of vr1, is it same with vdd!.
If they are same, I think you can keep them with no deviation, you can change the other MOS's Vth.

 

[Hughes]

www.mmb2.com.br

If you want the 'DeltaVt_MMB2' is the same for mp1 and MMB2, you should put this parameter into the model statement.

 

[Humungus]

No way with all other answers.

You've got to specify that those parameters are LOT variations.

LOT parameters have the same value every time they are instanced.

DEV parameters have different values in every intantiation.

LOT parameters represent the variations of the whole lot processed.

DEV parameters correspond to mismatch among similar devices.

 

[tracy_smile]

I think if you write like this,

.param DeltaVt_MMB2 = agauss(0,0.01,3)

.param DeltaVt_1=DeltaVt_MMB2

mp1 va va vr1 vr1 pch w=2.7u l=3u m=1 delvto=DeltaVt_1

MMB2 net25 va vdd! vdd! pch W=20.25u L=1u M=12
+delvto=DeltaVt_1

you may get the same Vth in every run.

 

[bharatsmile2007]

Hi all,

If u see the below line

.param DeltaVt_MMB2 = agauss(0,0.01,3)

what does 0,0.01,3 represent in agauss?

Thanks