[libre-riscv-dev] 130nm for the hackers : finally a reality ?

Staf Verhaegen staf at fibraservi.eu
Wed Jul 1 12:56:46 BST 2020

Luke Kenneth Casson Leighton schreef op wo 01-07-2020 om 12:02 [+0100]:
> ok.  180nm is 70,000 gates per sq.mm, therefore (square law), 130nm is
> double that.  (180/130 * 180/130).  so that's 1.4 million gates.

You have also count the area of the on-chip ram. Also be aware that ASIC gates is different from FPGA gates. ASIC gates are based on NAND2 standard cell, FPGA gates on LUTs. In my previous live I've seen quite some debate on how to convert them. I think 1 FPGA gate corresponds with 6-12 ASIC gates depending on architecture.
Cost for the 0.18um prototype was based on 36mm2 so in 0.13um this would correspond with 18mm2 so won't fit on the Sky130 runs.

> we'd really need to speak with Staf, as it means moving from October180nm with Eurocircuits, to November 130nm.

I would like to propose to not change the current NLNet defined projects for me and LIP6 in the mids of them.
I did spend quite some time on defining them and trying to guide them in order to be able to reach a successful tape-out. I did count on being able to finalize the milestones in the NLNet project and be paid for my work.

Currently it is also not fully clear what the conditions will be for the shuttle, if there are too many design you may not be taped, etc.
Current plan is also that you will only have around 40 pins and it is not clear if some of them are still needed for supply/ground for such a big prototype.
The package will also be BGA which is a pain to solder oneself.
For the 0.18um prototype we can go up to 208 pins for a QFP with 0.5mm pin pitch or even 256 pins for a LQFP with 0.4 pin pitch.
I have also seen talks about turning the 0.18um prototype into a higher volume SoC for a customer. It is not clear to me yet under which (commercial) conditions this could happen for Sky130.

We can agree to work on a Sky130 tape-out after the 0.18um prototype had been taped and target the first Sky130 run of 2021. Or other people can work in parallel on a Sky130 tape-out; this is open source and the more the merrier...


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