This seems to be one of the most commonly asked questions on the forum. I suggest you do some searching to see if you can find an answer already on the forums (rather than me searching for you).

Kind Regards,

Andrew.

Hello Andrew,I could not find a post for  Y axes to be gm/Id and X axes to be Id/W.

i have found some manual with using XVAL (which is transient of frequency domain) where as here we have DC sweep.

the algorithm i saw was to create 

gm/W versus Id/W

where we have to sweep the DC simualtion with W(width of transistor) which is not makes any sense and use XVAL which doesnt work for DC sweep.

Could you please  tell me the general steps?

Thanks.

Dear robert21,

I could not find a post for   Y axes to be   gm/Id and X axes to be Id/W.

You can define what ViVA Xl uses as the Y and X axes by using the calculator expression waveVsWave(). Did you try this or find it in the documentation? I found it pretty quickly robert21. It took me longer to create a test case!

I assembled a test case and this works fine for me. I defined the values of gm/Id and Id/W as:

gm_over_id,expr,(OS("/M0" "gm" "<results_directory>) / i("/M0/D" ?result "dc"))

id_over_W,expr,(i("/M0/D" ?result "dc") / VAR("W"))

I then defined the output waveform you wanted to plot as:

gm_over_id/Id_over_W,expr,waveVsWave(?x id_over_W ?y gm_over_id)

I was then able to plot the resulting waveform gm_over_id/Id_over_W as shown below as Figure 1. As verification that I was plotting the variables in the manner you requested, I exported variables gm_over_id and id_over_W as a function of their x values of vgate. I created the resulting plot in Figure 2 showing the same result as provided by ViVA XL.  I hope this helps robert21.

Shawn

Figure 1

Figure 2

Hello Shawn,yes your method of waveVsWave works great. Thanks.

 You have made the gm/id expression with one OS and one Idc param to construct the gm/id expression.

However when i try to construct  ft=gm/cgg (Vgs)  we have two OS param thats needs to be saved, but my ADEL allowes to save only one OP to be saved.
How can we  construct gm/cgg?

thanks

ADE (L included) allows more than one operating point parameter to be saved for a device. Just list the names (space separated) on the save op params form field. So I've no idea why you think you can only save one...

Andrew.

Hello Andrew, Thank you very much ,putting space in the OP ADEL  "gm cgg" allowed me to create gm/cgg in the calculator.

Thanks.

Hello Andrew, Thank you very much ,putting space in the OP ADEL  "gm cgg" allowed me to create gm/cgg in the calculator.

Thanks.