Post-simulation error

Dear jandk,

jandk said:

After extracting calibre for post-simulation, the simulation keeps reporting the following error: 

jandk said:

ERROR(CMI-2436): I0.XI18_XI14_XPM14: ''Pclm' = -1.40959 must be non-negative.
Why does this error occur in post-simulation, and how can I fix it?

In my experience, the error messages shown in the CIW relate to the design parameters of your post-layout based netlist devices and those allowed by their model. I don't know your specific circuit or device configuration, but if a single device in your schematic based netlist is split into a multiple finger device in your layout, there may be constraints on its model parameters that are violated depending on its layout parameters such as the range of lmax and lmin or its area (as your error indicates). As you probably are aware, a post-layout based netlist usually calls a difference device model than the pre-layout based netlist model. That, combined with the different area and device parameters of a set of post-layout devices comprising your single schematic device, can result in this type of error in a post-layout simulation. Often, your PDK has limits for the acceptable range of parameters for manufacturing or yield optimization.

I might suggest you examined how the parameters of the post-layout devices identified in the CIW compare to the corresponding device(s) in your schematic based netlist.

Shawn

Dear jandk,

jandk said:

After extracting calibre for post-simulation, the simulation keeps reporting the following error: 

jandk said:

ERROR(CMI-2436): I0.XI18_XI14_XPM14: ''Pclm' = -1.40959 must be non-negative.
Why does this error occur in post-simulation, and how can I fix it?

In my experience, the error messages shown in the CIW relate to the design parameters of your post-layout based netlist devices and those allowed by their model. I don't know your specific circuit or device configuration, but if a single device in your schematic based netlist is split into a multiple finger device in your layout, there may be constraints on its model parameters that are violated depending on its layout parameters such as the range of lmax and lmin or its area (as your error indicates). As you probably are aware, a post-layout based netlist usually calls a difference device model than the pre-layout based netlist model. That, combined with the different area and device parameters of a set of post-layout devices comprising your single schematic device, can result in this type of error in a post-layout simulation. Often, your PDK has limits for the acceptable range of parameters for manufacturing or yield optimization.

I might suggest you examined how the parameters of the post-layout devices identified in the CIW compare to the corresponding device(s) in your schematic based netlist.

Shawn

Thank you for your advice, it helps a lot. The number of fingers should not be a large value.