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General >> Tech Talk >> Estimating and planning
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Message started by Peruzzi on Feb 5^th, 2021, 4:20pm

Title: Estimating and planning
Post by Peruzzi on Feb 5^th, 2021, 4:20pm

How do you come up with your first rough estimate for how long it takes to design a circuit, its area, and current consumption?
In particular, say you had to add a high pass filter (to boost high frequencies) to a SERDES receiver, that wasn’t already there. Just a hand-waving approximation of how many weeks it would take to design, verify, layout, post layout verify, and get first samples from the foundry. How much current it would draw, and how big it would be. Say, for 45 nm.
Nobody’s going to hire you or me to do this. Just an approximation.
You’re not committing to any accuracy here. I appreciate it.
Thanks,
Bob P.

Title: Re: Estimating and planning
Post by Desi_iseD on Jun 17^th, 2021, 5:04am

Hi Bob,

that is very dependent on several factors:

-For Design: how many blocks do you need to change, how many designers are working on the project, how complex is the task, how experienced are the designers working on the task
Very easy tasks can be done in a few days, while complex tasks may take 2-4 month approximately; best is to plan the blocks individually and ask the designers assigned to it. And then add 30% planning buffer to the given number.

-For Layout: also very much dependent how much re-shuffling of the other blocks need to be done. If there is enough space and its a easy add on then it can take only a week. If a lot of re-shuffling or change of floorplanning needs to be done it can take several weeks. It is recommandable to ask the Layouters for the effort.

-For Verification: how many people are working on the verification, do you have a efficient optimized flow for it, is Testmode verification included, how many DV cases do you need to run. I would say you have to calculate at least 6 weeks for the DV

-Post Layout Verification & Optimization typically takes 2-3 weeks but is also dependent on the number of DV cases and amount/effort of optimization

-Finally you also need to include time for the Mask Order which typically takes 1 week

-Regarding Sample Time is very much dependent which priority you get in the fab and also about the individual fab and process times. I would say typically you wait 3-4 month from tape out till samples in house

-Regardarding area& current consumption this is typically done block wise and then summed up. If you already have a given layout and you just need to add something you can easily take the given numbers and just add the area/current consumption of the block added. If you start with a new product you typically have a spec where you need to make a rough estimate for each block upfront as block level specification

I hope that helps

Title: Re: Estimating and planning
Post by Peruzzi on Jun 17^th, 2021, 10:16am

Thank you. That's all I needed.
Bob P.