CDF parameter not found in sweep simulations

[Roger Light]

Hi,

For some of the work that I am doing at the moment, I would like to be
able to easily modify model parameters that are usually left fixed.

To do this, I have copied the existing device provided by my foundry and
then added a CDF parameter to the new device. In this case, I am trying
to add the "is" parameter to an n-well diode (nwd) provided by AMS.

I have added the "is" parameter to the Component Parameters section of
the CDF, and also to the spectre instParameters part of the Simulation
Information.

I have also created a modified model file which appears as:

==========

inline subckt new_nwd ( a c )
parameters area=1.0e-12 perimeter=1.0e-6 is=1e-5

new_wd ( a c ) diodeinsub area=area perim=perimeter region=off
model diodeinsub diode level=1 dskip=no \
is=is isw=2........
ends new_nwd

==========

This works fine in simulations - I can modify the "is" parameter and
observe the change.

My problem is that when I try to run a sweep simulation using the "is"
component parameter as the sweep variable I get the error:

Error found by spectre during DC analysis 'dc'.
D0 of new_nwd: Undefined parameter name 'is'.

Can anybody suggest what step I've missed out?

This is on ic 5.0.0.32 on Solaris.

Regards,

Roger Light

 

[Andrew Beckett]

The problem is that you're probably trying to sweep a design variable, which
is effectively a global parameter. You only have 'is' as an inherited (or
passed) parameter in the inline subckt.

So what you can do is have the instance of your n-well diode having the is
parameter set to a design variable in ADE, say "myis". Then sweep that.

Andrew.

On Thu, 20 May 2004 16:03:40 +0100, Roger Light
<roger.lightDOESNTLIKESPAM@nottingham.ac.uk> wrote:

Hi,

For some of the work that I am doing at the moment, I would like to be
able to easily modify model parameters that are usually left fixed.

To do this, I have copied the existing device provided by my foundry and
then added a CDF parameter to the new device. In this case, I am trying
to add the "is" parameter to an n-well diode (nwd) provided by AMS.

I have added the "is" parameter to the Component Parameters section of
the CDF, and also to the spectre instParameters part of the Simulation
Information.

I have also created a modified model file which appears as:

==========

inline subckt new_nwd ( a c )
parameters area=1.0e-12 perimeter=1.0e-6 is=1e-5

new_wd ( a c ) diodeinsub area=area perim=perimeter region=off
model diodeinsub diode level=1 dskip=no \
is=is isw=2........
ends new_nwd

==========

This works fine in simulations - I can modify the "is" parameter and
observe the change.

My problem is that when I try to run a sweep simulation using the "is"
component parameter as the sweep variable I get the error:

Error found by spectre during DC analysis 'dc'.
D0 of new_nwd: Undefined parameter name 'is'.

Can anybody suggest what step I've missed out?

This is on ic 5.0.0.32 on Solaris.

Regards,

Roger Light

--
Andrew Beckett
Senior Technical Leader
Custom IC Solutions
Cadence Design Systems Ltd

 

[Roger Light]

Hi Andrew,

The problem is that you're probably trying to sweep a design variable, which
is effectively a global parameter. You only have 'is' as an inherited (or
passed) parameter in the inline subckt.

Ok, I think that makes sense.

So what you can do is have the instance of your n-well diode having the is
parameter set to a design variable in ADE, say "myis". Then sweep that.

Yep, this works fine - I should have mentioned I could do this already.
I was mostly curious about why the other didn't work, which like I say I
think I understand now.

Thanks,

Roger Light