About a month and a half ago, I wrote a 5 part series of blog posts on the newly introduced Lynx Design System from Synopsys:
- Part 1 - Synopsys Lynx Design System Debuts at SNUG
- Part 2 - Lynx Design System? - It’s The Flow, Stupid!
- Part 3 - Strongest Lynx
- Part 4 - The Weakest Lynx
- Part 5 - The Mising Lynx - The ASIC Cloud
One key feature, the inclusion of pre-qualified technology and node specific libraries in the flow, was something I had pushed for when I was previously involved with Lynx (then called Pilot). These libraries would have made Lynx into a complete out-of-the-box foundry and node specific design kit … no technology specific worries. Indeed, everyone thought that it was a good idea and would have happened had it not been for resistance from the foundries that were approached. Alas!
In the months before the announcement of Lynx, I heard that Synopsys had finally cracked that nut and that foundry libraries would be part of Lynx after all. Whilst speaking to Synopsys about Lynx in preparation for my posts, I asked whether this was the case. Given my expectations, I was rather surprised when I was told that no foundry libraries would be included as part of Lynx or as an option.
The explanation was that it proved too difficult to handle the many options that customers used. High Vt and low Vt. Regular and low power process. IO and RAM libraries from multiple vendors like ARM and Virage. Indeed, this was a very reasonable explanation to me since my experience was that all chips used some special libraries along the way. How could one QA a set of libraries for all the combinations? So, I left it at that. Besides, Synopsys offered a script that would build the Lynx node from the DesignWare TSMC Foundry Libraries.
Two weeks ago, at the TSMC Technology Symposium in San Jose, TSMC announced their own Integrated Sign-off Flow that competes with the Lynx flow, this one including their libraries. Now it seems to make sense. TSMC may have backed out of providing libraries to Synopsys to use with Lynx since they were cooking up a flow offering of their own. I don’t know this to be a fact, but I think it’s a reasonable explanation.
So, besides the libraries, how does the TSMC flow compare to the Synopsys Lynx flow? I’m glad you asked. Here are the salient details of the TSMC offering:
- Complete RTL to GDSII flow much like Lynx
- Node and process specific optimizations
- Uses multiple EDA vendors’ tools (Synopsys mostly, but also Cadence, Mentor, and Azuro)
- Available only for TSMC 65nm process node (at this time)
- No cost (at least to early adopters … the press release is unclear whether TSMC will charge in the future)
- And of course, libraries are included.
In comparison to Synopsys’ Lynx Design System, there were some notable features missing from the announcement:
- No mention of anything like a Management Cockpit or Runtime Manager
- No mention of how this was going to be supported
- No mention of any chips or customers that have been through the flow
To be fair, just because these were not mentioned, does not mean that they are really missing, I have not seen a demo of the flow or spoken to TSMC (you know how to reach me) and that would help a lot in evaluating how this compares to Lynx. Still, from what I know, I’d like to give you my initial assessment of the strength of these offerings.
TSMC Integrated Signoff Flow
- The flow includes EDA tools from multiple vendors. There is an assumption that TSMC has created a best-of-breed flow by picking the tool that performed each step in the flow the best and making all the tools work together. Synopsys will claim that their tools are all best-of-breed and that other tools can be easily integrated. But, TSMC’s flow comes that way with no additional work required. (Of course, you still need to go buy those other tools).
- Integrated libraries, as I’ve described above. Unfortunately if you are using any 3rd party libraries, you’ll need to integrate them yourself it seems.
- Node and process specific optimizations should provide an extra boost in quality of results.
- Free (at least for now)
Synopsys Lynx Design System
- You can use the flow with any foundry or technology node. A big advantage unless you are set on TSMC 65nm (which a lot of people are).
- Other libraries and tools are easier to integrate into the flow I would think. It’s not clear whether TSMC even supports hacking the flow for other nodes.
- Support from the Synopsys field and support center. Recall, this is now a full fledged product. Presumably, the price customers pay for Lynx will fund the support costs. If there is no cost for the TSMC flow, how will they fund supporting it? Perhaps they will take on the cost to get the silicon business, but that’s a business decision I am not privy to. And don’t underestimate the support effort. This is much like a flow that ASIC vendors (TI, Motorola/Freescale, LSI Logic), not foundries, would have offered. They had whole teams developing and QA’ing their flows. And then they would be tied to a specific set of tool releases and frozen.
- Runtime Manager and Management Cockpit. Nice to have features.
- Been used to create real chips before. As I’d said, the core flow in Lynx dates back almost 10 years and has been updated continuously. It’s not clear what is the genesis of the new TSMC flow. Is it a derivative of the TSMC reference flows? Is it something that has been used to create chips? Again, I don’t know, but I’ve got to give Synopsys the nod in terms of “production proven”.
So, what do I recommend. Well, if you are not going to TSMC 65 nm with TSMC standard cell libraries, then there is not much reason to look at the TSMC flow. However, if you are using the technology that TSMC currently supports, the appeal of a turnkey, optimized, and FREE flow is pretty strong. I’d at least do my due diligence and look at the TSMC flow. It might help you get better pricing from TSMC.
If anyone out there has actually seen or touched the TSMC flow, please add a comment below. Everyone would love to know what you think first hand.
harry the ASIC guy