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Simulators >> Circuit Simulators >> Specifying subcircuits for temperature sweep
https://designers-guide.org/forum/YaBB.pl?num=1674096717

Message started by kemiyun on Jan 18^th, 2023, 6:51pm

Title: Specifying subcircuits for temperature sweep
Post by kemiyun on Jan 18^th, 2023, 6:51pm

Hi, I'm trying to find the best practices for sweeping temperature for some subcircuits of my design while keeping other sections at another constant level. What is the best way of doing this? **EDIT: Forgot to add, I'm trying to do this in spectre, version should be latest, but I will check again tomorrow.

More detailed problem definition: I have a positive temp co current generator that feeds a current into an oscillator that has a negative temp co characteristic so the current generator compensates for the temp variation to a degree. I would like to simulate the temp co effects of these subcircuits on the frequency without separating them or modifying the schematic.

My naive solution that I don't like: I can easily separate these circuits and buffer them or just feed sim output from one to the other. I don't want to do this. I don't have a reason, I just don't like it ;D . It's not elegant.

Several related solutions I could find from Cadence forums: I've found the following solutions, but these are pretty old. I would like to check whether there are better ways available in newer versions.

https://community.cadence.com/cadence_technology_forums/f/custom-ic-design/25211/temperature-variation-to-only-one-fet
https://community.cadence.com/cadence_technology_forums/f/rf-design/43557/individual-temprature-setting-in-cadence-virtuoso
I do not like the solution above, because I would have to define it for a lot of devices which is tedious and requires actual parameter changes in the circuit.

https://community.cadence.com/cadence_technology_forums/f/custom-ic-design/26780/set-different-temperature-in-a-complete-chip
I think this solution is closer to what I want but it's a very old response and personally I have a bit of a dislike for MTS stuff (not a rational dislike, I just distrust stuff I don't use as often and my past experience with MTS was problematic in a big project).

I would appreciate any advice on how to do it, or where to look for more info, or any keywords that would put point me in the right direction.

Thank you.

Title: Re: Specifying subcircuits for temperature sweep
Post by smlogan on Feb 17^th, 2023, 5:12pm

Dear kemiyun,

> I think this solution is closer to what I want but it's a very old response
> and personally I have a bit of a dislike for MTS stuff (not a rational dislike
> , I just distrust stuff I don't use as often and my past experience with MTS
> was problematic in a big project).

This is a more recent Forum post with references to documentation and a video on the use of MTS with local scoped models. It is relatively recent and the recommended manner to allow the simulation of subcircuits with differing models (or temperatures).

https://community.cadence.com/cadence_technology_forums/f/custom-ic-design/47567/simulation-for-different-temperature-of-parts

Shawn

Title: Re: Specifying subcircuits for temperature sweep
Post by kemiyun on Feb 20^th, 2023, 7:10am

Thank you. It seems like the way to go is still using MTS and there isn't really a new methodology to handle it.