Hspice programming for nmos simulation

[sam139]

Hello guys,

I am a beginner with hspice and please help me with this problem. I want to simulate Ids vs.Vds for Vgs = 0, 0.2, 0.4 for a nMOS transistor in a 65 nm process with W/L = 120 nm/80 nm. The maximum value of V ds is 1.0V.
Kindly let me know how to go on with programing this problem.

Any help would be appreciated.

 

[gs65]

.include (library path)
Vdd1 vdd 0 dc 1v
Vds vd 0 dc 1v
Vgs vg 0 dc 0.4v
Mn1 vo vg vd vd nmos
.dc vds 0 1 0.1 sweep vgs 0 0.2 0.4
.ends

 

[FvM]

gs65, I wonder where you picked up these SPICE lines. And also, what you'll answer if someone asks why they are completely wrong?

.include (library path)
Vdd1 vdd 0 dc 1v
Vds vd 0 dc 1v
Vgs vg 0 dc 0.4v
Mn1 vo vg vd vd nmos
.dc vds 0 1 0.1 sweep vgs 0 0.2 0.4
.ends

 

[gs65]

@fvm, there was some syntax error in my previous code. i have checked the output for the below.

*nmos iv characteristics
*library path
.include C:\Users\Ananya\Desktop\h_spice\180micron.txt

***********component declearations******************
*voltage elements declarations

vds vd gnd dc 1.8
vgs vg gnd dc 1.0
vsb vb gnd dc 1.8
vss vs gnd dc 0

*m1-component declaration-user defined
*nmos-instantiation of model 	NMOS which is already present in the library

mm1 vd vg vs vb nmos w=2u l=0.18u
****************************************************

*dc_analysys


.dc vgs 0 1.8 0.001 sweep vgs 0 0.2 0.4

* for selecting the output current ids
.probe dc i(mm1)

.end

 

[FvM]

The circuit looks better, but forward biasing the substrate with 1.8 V usually burns any real MOSFET. The substrate of a NMOS transistor has to be connected to the most negative node, in this case gnd.

You can watch the currents in your simulation,. there should be no substrate current.

 

[gs65]

@fvm
Ok .
I have a doubt.. Substrate should be connected source or lowest potential

 

[FvM]

Yes, it should. In CMOS IC technology, N and P substrates are "automatically" connected to VSS and VDD respectively.