Sunday, April 19, 2015

Moore's law - A journey of 50 years

50 years of innovation! 50 years of quest with complexity! 50 years of Moore's law! Yes, April 19th is an important date for the semiconductor industry. It was on this date in 1965 that a paper was published citing Gordon Moore's observation - the no. of transistors on a given silicon area would double in almost every two years. The observation turned to be a benchmark and later a self fulfilling prophecy that is chanted by everyone whether an aspirant wanting to be a part of this industry or veteran who worked all throughout since the time when the law was still an observation! I myself remember my first interview as a fresh grad where I was asked the definition & implication of this law. It may not be a surprise if there is a survey done on one name that people in this industry have read, heard or uttered the most in their careers and the result would be MOORE unanimously!
The below infographic from Intel would help you appreciate the complexity that we are talking about –

In this pursuit to double the no. of transistors, there were major shifts that the industry experienced. Let's have a look at the notable ones that had a major impact -
Birth of EDA industry – As the numbers grew it was difficult to handle the design process manually and there was a need for automating the pieces. While the initial work in these lines happened in the design houses, it was soon realized that re-inventing the wheel and maintaining proprietary flows without considerable differentiation to end products wasn’t so very wise. This lead to the birth of the design automation industry that today happens to be the lifeline of the SoC design cycle.
Birth of the fabless ecosystem – The initial design houses had the muscle to manufacture the end product while allowing some contract manufacturing for the smaller players. This setup had its own set of issues discouraging startups.  Also, maintaining the existing node while investing in R&D for next gen nodes was unsustainable. It was only in the late 80s when Morris Chang introduced the foundry model that the industry realized fabless was a possibility. Since then, all stakeholders of the ecosystem have collaborated towards realizing the Moore’s law.
Reuse – As the transistors scaled, the turnaround time to design should have increased, but, to keep a check on the same, reusability was adopted. This reuse was introduced at multiple levels. Different consortiums came forward to standardize the design representations & hand offs. Standards helped in promoting reuse across the industry. Next was design reuse in form of IPs. For standard protocols the IPs are reused across companies while for proprietary ones reuse within the organization is highly encouraged. Reuse has played a significant role in continuing the pace that Moore’s law suggests.
Abstraction – When the observation was made, the design were still at transistor level and layouts done manually. Due to the need to sustain the rising complexity, it was realized to move to next level of abstraction i.e. logic gates followed by Register Transfer level where the design is represented in HDLs and synthesized to gates. Today the industry is already talking about a still high level synthesizable language.
Specialization – The initial designs didn’t require a variety of skill set as it is today. Given the evolution of the design cycle and the quantum of responsibility at every stage, there was a need to bring in specialists in each area. This lead to RTL designers, verification engineers, gate level implementation engineers and layout engineers. Today the overall team realizing a design runs into hundreds of engineers with varied skill set for a complex SoC involving EDA, foundry, reuse & abstraction.
Throughout these 50 years, there were many a times when experts challenged the sustainability of Moore’s law. Most of them had a scientific rational endorsing their argument. However, the collective effort of the industry always was able to find out an answer to those challenges – sometimes through science, sometimes through logic and sometimes through sheer conviction!
Long live Moore’s law!