Cad-view
From Circuitopedia
Circuit-O-pedia: Circuit Open Encyclopedia
The CAD view
Note: This was first written for DAC-2007, Wild and Crazy Ideas Session. The authors are Varun Aggarwal and Una-May O'Reilly. The article is reproduced in its original form. CANDI has been now re-christened as Circuitopedia.
Is World Wide Web the solution to the unrelenting analog design automation?
In the last few years, World Wide Web has ushered a revolution by becoming a collaborative knowledge-base and an interface for open-source software development and use. Can WWW provide a solution to simplifying and automating analog design, which has been considered art-form and even black-magic, a magic few people know!
We think the answer is YES. Rewind to the 70’s, the art-form reputation of analog enthused AI practitioners like Stallman and Sussman to make a system to heuristically solve circuits. This was followed by tools like IDAC, OASYS and BLADES, which were knowledge-intensive systems and used human-design knowledge to code static design plans and rules for expert systems. Though these systems were very impressive, they just didn’t scale since each topology (and even at times technology) needed new design knowledge, a traditional problem with all Knowledge-based Systems.
Fast-forward to the 90’s, optimization was identified as a method to size circuits using circuit equations. Again, getting accurate equations didn’t completely yield to automation and the approach remained knowledge-hungry and severely bottlenecked for transient and non-linear equations. Riding on the back of Moore’s Law, came in simulation-based approaches, since SPICE was now fast enough to be run inside the loop of optimization, eliminating inaccuracies and need for knowledge. The simulation approach was general, but definitely slower than having an expert system for a particular circuit. Moore’s law may not help any further, for shrinking technology is not only giving more computation power, but also asking for more of it due to more complex simulations. More recently, came in geometric programming, which was very quick due to structural approach of optimization, but once again knocked for knowledge, circuit equations in posynomial form.
The need for knowledge has remained a bottleneck, leading to surrender to simulation-based approaches, which also infact could be sped-up by use of knowledge. Similarly, are students of analog-design starved for knowledge, for knowledge is been scattered into grey-areas of a few, making the learning-curve very slow.
The WWW now offers an opportunity to make analog design fast and easy, to allow it to manifest in its full glory (than playing an old-dwindling father to digital). Come 2000, a knowledge base like Wikipedia is put together entirely by a distributed community, the apache web-server is developed distributedly on the web. Knowledge-based AI is featuring a return, semantic web allowing knowledge representation for expert systems, and Minsky’s Open Mind Common Sense Project attracting more than 70,000 responses. Technical communities have also realized the potential of this, with collaborative knowledge base like Open-Wetware and Bio-Bricks Foundation.
We envision CANDI, a knowledge-base and integrated software environment for analog design. The spirit of CANDI with all the nut and bolts is captured in Figure 1. The knowledge vertical accumulates knowledge for both manual-sizing and automatic sizing approaches. Knowledge Representation is an important issue for different approaches need knowledge in different forms such as posynomials, expert rules, textual design plans for humans, equations, etc. Creating templates for knowledge gathering, which minimize effort and repeatability for user, allow easy conversion across multiple uses is the first task for the knowledge-base. The knowledge-base shall then evolve for itself, getting used/contributed by analog designers, analog design classes in universities, etc.
A complementary, but important vertical is that of an integrated software environment, which directly plugs in the knowledge created on web. These two verticals together can give an end-to-end solution for enabling both manual and automatic approaches of analog design. One of the most interesting emergent effects out of CANDI will be the symbiosis of manual and automatic approaches, as they would inform each other and create a nice partnership between man and machine.
For analog design to transcend the current limitations, CANDI is a necessity. How would it effect the interests of the SOC and CAD industry? Would analog design students stop thinking? The free-software-movement answers this well. We are still creating more and better software engineers even when plethora of free software/code available on the web. The transition has been from reinvention of wheel every time to build the car structure over the wheel. Has the software-services or software product companies died? No, not at all! CANDI would simply make the design cycles shorter for all and create a higher-level playing field for all SOC companies, there will be now a strata of knowledge available for all and innovation would be needed at a higher level. The CAD industry would be in a mood to rejoice, for their tools will be used since the knowledge to plug-in is available online. And again, CANDI would just create a new level playing field, there will be tools and solutions specialized enough to get out of the domain of CANDI.
Thus, we call upon all from academia and industry to come together to make CANDI reality and unleash the power of analog design.
