how to measure the current value in the hspice?

[triquent]

I wrote a hspice code to simulate and plot the nmos' I-V curve. how can i use .measure command to measure and directly give out the current value at specific vgs and vds. i tried a lot of times, still don't work.
ex.
.measure dc i1 when vgs=1.5 vds=3

 

[leo_o2]

I think you need to check in HSPICE help:
It should be like: .meas IM find I1(...) when Vds=.. Vgs=..

 

[sunking]

add a little Res such as 1m and test the voltage

 

[Hughes]

Why use measure? I think a print statement is ok if you make both Vgs and Vds fixed. If you do prefer measure, please make Vgs (or Vds) a fixed value, and use measure to find the Ids at a given Vds (or Vgs) value.

 

[stefano2m]

Use a DC voltage source of 0V in series with the source or drain and plot the current.

 

[Hughes]

.measure dc i1 when vgs=1.5 vds=3

What is I1? The drain current of mosfet M1 is I1(M1). In addition, do not use two when clause in a measure.

 

[cmosbjt]

stefano2m is correct, and that is the convenient and reliable way.

 

[triquent]

this is the original code. anyone can help me to measue the mos current i(m1) by using .meas command? tried, but still not working.
$-----
.option
.param vd=3 vg=1.5 vs=0
$-------
vd1 d 0 vd
vg1 g 0 vg
vss vss 0 vs
m1 d g vss vss ns w=10 l=0.3
$-----
.dc vd1 0 3 1
$sweep vg1 1 3 0.5
$.probe i(mn1)
.meas DC i1 find i(m1) when vd1=1
$ vg1=1.5
$-------
.end

 

[leo_o2]

Try this one

Meas example
.option post list
.param avd=1
.param avg=1
vd1 d 0 avd 
vg1 g 0 avg 
vss vss 0 vs 
m1 d g vss vss modn w=10u l=0.3u
*NMOS model here
.dc avd 0 3 1 
.probe i1(m1) 

.meas DC IMeas find i1(m1) when v(d)=1

.end

 

[always@smart]

i have another option to see id when vd=1 :

$-----
.option
.op $print the operating condition
.param vd=1 vg=1.5 vs=0 $set the Initial condition vd=1
$-------
vd1 d 0 vd
vg1 g 0 vg
vss vss 0 vs
m1 d g vss vss ns w=10 l=0.3
$-----
.dc vd1 0 3 1

.trans 10ns 1000ns $analysis the transient response
$-------
.end

after the netlist is simulated , you can either see from :
1. operating conditaion in the "list file "
2. run the "Avanware" and open ".tr" file and select i(ds) in "current section"

hope this helps

regards,
smart

 

[Hughes]

Here is the netlist with minor modification:

$----- 
.option scale=1u post
.param vd=3 vg=1.5 vs=0 
$------- 
vd1 d 0 vd 
vg1 g 0 vg 
vss vss 0 vs 
m1 d g vss vss ns w=10 l=0.3 
$----- 
.dc vd1 0 3 1 
$sweep vg1 1 3 0.5 
$.probe i(mn1) 
.meas DC i1 find i(m1) when v(d)=1 
$ vg1=1.5 
$------- 
.model ns nmos level=1
+ vto=0.6 gamma=0.45 phi=0.9
+ nsub=9e+14 ld=0.08e-6 uo=350 lambda=0.1
+ tox=9e-9 pb=0.9 cj=0.56e-3 cjsw=0.35e-11
+ mj=0.45 mjsw=0.2 cgdo=0.4e-9 js=1.0e-8
.end

The key problem is that you should use when v(d)=1 rather than vd1=1.

After simulation, you can open the '*.ms0' file and see the results:

$DATA1 SOURCE='HSPICE' VERSION='2001.4' 
.TITLE '$-----'
 i1 temper alter#  
  4.273e-03   25.0000    1.0000