Monthly Archives: June 2011

Connect with Converter Passion at IWADC 2011



Anyone planning to attend IWADC 2011 – the international workshop on ADC and data converters – in Italy the coming week?  Then make sure to connect, and you may win the Connect-with-Converter Passion prize for IWADC 2011. The reward is to have yourself mentioned here on the blog (see winners from last years NORCHIP and ICECS here and here), and the only thing you need to do to win is to be the first attendee to locate me during the conference and claim the prize. Besides announcing and introducing the winner of the CWCP,  I also plan to highlight a few interesting papers, pick up the conference “vibes” and share it in my reporting from the conference. I’ll be interested to talk to all of you, so even if you didn’t win the CWCP race I will be very happy to hear what you have to say about the conference, tech blogs, or the data converter field in general. What are your views on ADC FOM, the data converter market and scientific trends for the next decade, and more …

Look for this face

If you haven’t found me before, a safe bet is around the High-efficiency Data Converters session (Thursday 14:15–15:45) where I will present my first contribution An empirical approach to finding energy efficient ADC architectures , or at the Poster Session II for which I am chair on Friday, and where I will also present my second contribution Using Figures-of-Merit to Evaluate Measured A/D-Converter Performance. For more details, see the “Going to Italy, Yes, Yes, Yes!” post, and the conference program.

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Is A/D-converter research becoming a purely academic exercise?


Figure 1. ADC research origin (first author). Absolute amount of papers.

Figure 2. ADC research origin (first author). Relative amount of papers.

Is A/D-converter research becoming a purely academic exercise? Well, looking at the statistics for scientific ADC implementation papers shown in the two graphs above, that certainly seems to be the future for open A/D-converter research. What are the implications, and does it matter?

Figure 1 shows the number of published ADC papers over time, separated into type of origin, as determined by the affiliation of the first author {AcademicInstituteIndustry}. Although a simplification, it is believed to be a fairly accurate indication of where most of the work was done. The term Institute is referring to entities that are neither universities nor traditional companies, i.e., organizations like IMEC. Figure 2 shows the relative amount of contributions from each sector, based on the same data.

Where is corporate ADC research going?

Figure 2 paints a very clear picture: The industrial “market share” of scientific  publications has had a noisy but linear negative trend almost from the start. If the trend holds – and there are actually no signs in the graph that it won’t – there will be no scientific ADC papers from industry published after year 2020–2025! At least not with the first author being from the industry.

I find that quite remarkable and slightly counter-intuitive. Aren’t academic scientists the first to explore the un-explored, and after having spent a lot of time weeding out the less fruitful approaches, they finally come up with something that works? After which the industry wakes up and jumps on the bandwagon? The ADC field appears to do exactly the reverse: After initially been doing 100% of the work, the industry is now gradually letting the universities take over the field.

We are talking about the open research literature here, so it doesn’t necessarily mean that there is no activity within the companies. It just isn’t getting out. So, what do you think:

  • Does the industry feel that there is nothing more to improve or research? If so, why can academic papers still get published?
  • Is the industry increasingly putting a lid on their research to survive the competition?
  • Or is it just a better business to focus on shifting parts, while letting universities innovate and then pick new solutions as they get published?

Quality – not quantity?

On the other hand, industrial contributions report excellent results. A state-of-the-art figure-of-merit (FOM) is a dream target for many research groups. In view of the dwindling industrial publication count, it is interesting to note that the performance of top industrial contributions does not seem to suffer: The overall best Thermal FOM for Nyquist converters was reported for a SAR design by Analog Devices [1], and the scientifically most sought-after world record “Walden FOM” was reported by a group of authors where three out of six were also affiliated with companies (Philips and Axiom IC) [2].

Poll

Additional info

The data set used is from an exhaustive survey [3] of ADC papers in journals and at conferences central to the field. After a recent update, the survey covers almost 1600 scientific papers or nearly all ADC implementations ever measured and reported scientifically since 1974. Hence the historical trends shown here should be definitive.

Want to know more?

Do you want to know more about ADC research trends? Are you making strategic decisions relating to data converter technology, research or business? The plots in Figure 1 and Figure 2 are taken from a larger report on ADC research trends that I’m currently working on for ADMS Design AB. The report will be available for purchase after the summer. It will survey ADC research trends from many different angles, and present valuable and truly unique information that is not offered anywhere else.

If you wish to be notified when the report is available, or want to know more, you can contact me at ADMS Design AB.

ADMS Design AB also offers full-custom surveys relating to commercial and scientific ADC trends, technology and business.

References

[1] C. P. Hurrell, C. Lyden, D. Laing, D. Hummerston, and M. Vickery, “An 18 b 12.5 MS/s ADC with 93 dB SNR”, IEEE J. Solid-State Circuits, Vol. 45, pp. 2647-2654, Dec., 2010.

[2]    M. van Elzakker, E. van Tuijl, P. Geraedts, D. Schinkel, E. Klumperink, and B. Nauta, “A 1.9μW 4.4fJ/Conversion-step 10b 1MS/s charge-redistribution ADC,” Proc. of IEEE Solid-State Circ. Conf. (ISSCC), San Francisco, California, pp. 244–245, Feb., 2008.

[3] B. E. Jonsson, “A survey of A/D-converter performance evolution,” Proc. of IEEE Int. Conf. Electronics Circ. Syst. (ICECS), Athens, Greece, pp. 768–771, Dec., 2010.

Reader question: Shouldn’t the (effective) bandwidth of the ADC or DAC also be reported in the titles?


Ameya Bhide posted a question in the Q&A section. Ameya wrote:

Hi Bengt,

After being lost in the world of Converters for a while, I always have this fundamental question as follows:-

Industries, Publications always talk about GSamples/sec of an ADC or a DAC and the higher the rate, better the converter is. But very few talk about the Bandwidth in the title of the ADC. Even in publications, I always see the title as ” An XGsamples/sec ADC” where as I think it should be “An X Gsamples/sec Y Mhz BW ADC” since many of these converters do not retain performance up to Nyquist.

Even when looking at the TI ADC’s I need to search the data sheet to find the real bandwidth of the ADC. Shouldn’t the sample rate and BW be always reported together so that one quickly understands what the capabilities of the ADC are?

Could you comment on this?

Thanks,
Ameya

Good question Ameya, and one that touches on a broader topic (scientific reporting practices) that I’ve been planning to bring up for a while. This is a good starting point. Perhaps your question was mostly concerning data sheets? Either way, I’d like to broaden it to include scientific papers as well.

So blog readers, what do you think?

  • Is there an inflation in paper/data-sheet titles?
  • Should we require paper titles to more accurately describe the actual bandwidth of the ADC?
  • Is effective resolution bandwidth (ERBW) the best measure?

If there is an inflation, and a practice to boost performance in the titles, what will happen to the pioneers which put more complete (potentially less impressive) information in the titles? Rejected papers and loss of business? Is the target audience really that gullible? Don’t they read the content of a data sheet or paper? How long can a paper/data-sheet title be 😉 … etc.

Reader question(s): Novelty of folding amplifier ADC architecture, big houses approach to external innovations, and academic vs. commercial specs


Blog reader Cole posted a question in the Q&A section, and I felt it was well worth a separate post:

Hi Dr. Jonsson, I am wondering the following things in general about the ADC industry:

–Are folding amplifiers a new concept? Why when I look at the TI website, for example, they do not sell any ADCs with a folding amplifier architecture?
–How open are the big houses to outside designs? If a small design house comes up with someone innovative, do the big houses adopt, buy-out, or ignore the small houses?
–What is the main difference between academic specs and industrial specs? How would I “convert” between the two? It seems like when I read academic papers, they claim high speeds at a certain bitrate, but industrial numbers all seem a bit more conservative (i.e. MSPS rather than GSPS).

As you can see, there are several interesting questions in there. What do you think? How hot are folding ADCs today? Do you have any experience from start-up innovation in relation to the big companies? How do you translate between data sheet specs and academic paper performance?

Anyone from “the big houses” wish to comment? How would you handle great innovations emerging in a small start-up external to your company? Adopt, buy-out or ignore? And how should we view commercial data sheet specs compared to scientific papers? Should we even try to “translate” between the two, or are these better seen as parallel universes?