How to compare the before and after extraction values of resistance and capacitance?

Vishesh Gupta said:

he capacitance used is a nmos capacitor. Is there any way I can compare the values of this capacitor before and after extraction (maybe a table that I can get)? I also want to know how the algorithm in the software has treated the capacitor? In other words, does the software breaks the capacitor in a pi network or star network, etc. in the extracted view.

If the capacitor is an nmos capacitor, then the parasitic extraction is not doing anything. There's no algorithm to apply here - what would happen is that your LVS tool will recognise the device, measure various parameters (such as drain/source areas and perimeters, LOD effects, Well proximity etc) and then these appear in the extracted netlist.

Parasitic extraction tools extract interconnect and may indeed generate a set of distributed RC (fracturing the interconnect based on length, change of layer, etc - some of which is under user control) - but that's not what is going on here (and exactly what it does is dependent on which extraction tool you're using, and the precise algorithms are likely to be proprietary; most will use some pattern matching based approach, but may use field solvers for more accurate capacitance extraction where needed).

Andrew

Hi Andrew,

Thanks a lot for the reply! Your information is really helpful.

Q1)

Andrew Beckett said:

what would happen is that your LVS tool will recognise the device

Will I be able to see the capacitance of the device in the parasitic extraction netlist and will it be included with the other cap parasitics list or in a sperate list?

Q2)

Andrew Beckett said:

Parasitic extraction tools extract interconnect and may indeed generate a set of distributed RC (fracturing the interconnect based on length, change of layer, etc - some of which is under user control)

I want to learn more about the "fracturing of the interconnect", can you please help me with something?

Regards,

Vishesh

Vishesh Gupta said:

Will I be able to see the capacitance of the device in the parasitic extraction netlist and will it be included with the other cap parasitics list or in a sperate list?

As I said in your other post, this depends on whether the device is modelled by specifying the w and l (which I would expect) - it may be that the actual capacitance doesn't appear in the netlist; I can't answer that as it depends on your LVS rules and design kit.

Vishesh Gupta said:

I want to learn more about the "fracturing of the interconnect", can you please help me with something?

On the Quantus form, click on the Extraction tab. it's the Max fracture length field - so hit the Help button and read the documentation on that.

Andrew

Hi Andrew,

Thanks a lot for the reply!

Andrew Beckett said:

so hit the Help button and read the documentation on that.

I got the following:

I know it is silly but can you please help what am I doing wrong here?

Regards,

Vishesh

After using the Help button, use ctrl-F and search within the box at the top right of the page. This willl search within the page, rather than the search box at the top which should search the Quantus documentation (not sure why it's not). but really searching within the page should be sufficient.

Andrew

After using the Help button, use ctrl-F and search within the box at the top right of the page. This willl search within the page, rather than the search box at the top which should search the Quantus documentation (not sure why it's not). but really searching within the page should be sufficient.

Andrew

Hi Andrew,

Thanks a lot!

Regards,

Vishesh