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Analog Angle Blog

Is Analog-IC Design Still So Special?

I often like to think about and question so-called “conventional wisdom,” since so much of it is built on statements or facts that are no longer true, or perhaps were never really true — but were repeated so often they just seemed to be accepted as true.

One of the many such chunks of conventional wisdom is that designing and fabricating an analog IC is in many ways very different than a digital IC. To cite a few examples:

  • The tools just aren’t as good; lots of designer experience is needed to balance the tradeoffs;
  • Processes are quite different and often specialized;
  • Feature size and die size are not driving factors;
  • It's not about how many active devices you can cram onto the die, since many analog ICs only need a few (some leading analog ICs have about a dozen active devices);
  • Thermal issues (drift, compensation, balance), and matching of key structures (such as gain resistors) are major design concerns;
  • Packaging is smaller, and pin (lead) count is usually on the lower side, compared to digital ICs;
  • Test fixtures and issues are different.

Were these statements true? In general, yes. There's lots of well-documented material and experience to verify them, no doubt about that.

But are they still true, and if so, to what extent? What made me think about this was a recent interview in EETimes with Louis DiNardo, the new CEO at Exar. He maintains that much of analog design is no longer so unique, that foundries can do a lot of the fab (no need for in-house facilities), and the tools have improved to where the “black magic” aspects of analog IC design are less of a factor.(See: Exar CEO Talks Analog, China, IoT.)

Is he right? Or is he just trying to rationalize Exar's technology and business model?

My view is this: As in most technical discussions, the answer is not black and white. There are shades of grey (but not quite 50 of them, thank goodness!), which depend on what you are trying to do. For a basic, moderate-performance analog circuit, he may have valid points.

Secret Sauce!

Secret Sauce!

But when you get to power-related ICs and regulators (even at low-power levels), low-noise amplifiers, RF PAs, higher-resolution converters, higher-speed amplifiers and converters, medium/high speed drivers, or… well, the list goes on, there are lots of cases where the IC design has lots of tricky tradeoffs, quirks, and so-called secret sauce.

The reality is that when you add up the segments that these more-challenging analog ICs represent, they add up to a significant part of the market, if not a majority (it also depends if you count by unit volume versus revenue, too).

For so-called commodity parts (sometimes derided as “low-hanging fruit”), DiNardo may be right. But for the many specialized or higher-performance analog-centric ICs, which truly differentiate a system's overall performance and thus make it competitive or distinctive to customers, I don't think so.

What's your sense of the situation? Is analog-IC design still so different than digital-IC design, or is it mostly a myth that the analog companies want to sustain?

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8 comments on “Is Analog-IC Design Still So Special?

  1. Scott Elder
    August 22, 2013

    I read Lou's comments and I think he was talking about ownership of fab technology, not whether analog design requires unique talents.  In which case I would agree.  But, if anyone thinks analog design skills have lost their value, one only needs to look at the numbers to see that is a myth.

    EXAR Revenue for the past several years is about $125 Million at ~52% gross margin.

    Analog Devices and Linear Tech are at $2.7 B and $1.2 B with 65% and 75% gross margin respectively.  So if analog talent is so unimportant today, why hasn't Exar gone after a piece of the now-easy $4B in revenue?  Another $100 Milion for EXAR should be easy pickings at 52% margin off that $4B, right?

    That being said, it is easier today to do a lot of traditionally hard analog.  Things like a simple buck or boost regulator, 8-10 bit ADCs, etc. can be knocked out fairly quickly and cost pennies.  That just means that one can't sit still.  Today it is about complex analog systems, not one-upping a competitor with another percentage point of power efficiency.  I think this has always been the case though.  Its the reason lots of cars still come from Detroit, Stuttgart, and Munich and not China even though car technology has been around for over 100 years.

    FYI.  On the EXAR website today they have a major banner proclaiming Exar “Enters the Precision Analog Market…” This is a result of having acquired one of those fabless analog “black magic” companies.

  2. Brad_Albing
    August 23, 2013

    @Scott – re “Enters the Precision Analog Market…” — my hunch is that Exar is pushing into that area because Intersil (my former employer) is moving away from that area.

  3. SunitaT
    August 24, 2013

    To add to the design challenge, device properties often vary between each processed semiconductor wafer. Device properties can even vary significantly across each individual IC due to doping gradients. The underlying cause of this variability is that many semiconductor devices are highly sensitive to uncontrollable random variances in the process. Slight changes to the amount of diffusion time, uneven doping levels, etc. can have large effects on device properties.

  4. Brad_Albing
    August 26, 2013

    Hmm… or maybe Exar is looking to combine forces with my former employer… hmm….

  5. Netcrawl
    August 27, 2013

    @Brad you're right they trying to bring something big in the industry. Exar's recent acquisition of Cadeka Microcircuits boost Exar's product portfolio, providing the company with technology it need to enter the precision analog market.

    Cadeka provide precision operational amplifiers and data converter products to a wide array of big electronic players in some important areas of tech industry- aerospace, medical electronics and industrial control space. I think the purpose of the acquisition is  to gain a quick access to a “new market”, it provide Exar a shortcut to enter a new market. Its probably the most quickest way to gain strong ground in the highly lucrative precision analog market. 

  6. samicksha
    August 27, 2013

    As they are more related with the physics of the semiconductor devices such as power dissipation, and resistance, fidelity of analog signal amplification and filtering is usually critical and as a result, analog ICs use larger area active devices than digital designs and are usually less dense in circuitry. The improvement is atleast we dont need to design IC using hand calculation..

  7. RedDerek
    August 27, 2013

    I remember Exar as the low-cost function generator IC, XR2200 (something). That was their biggest IC that I still see being used today. For them to move into the new market will be interesting to see how they compete against TI, Maxim, and Linear. They will have to compete on the price for the same performance. I just do not see them as high performance these days.

  8. SunitaT
    August 31, 2013

    I think one more major difference is we usually find Digital cell libraries built for particular process but its very hard to build analog libraries. Moreover their are tools which helps us to automate digital design flow but that is not the case with analog design.

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