Category Archives: DAC

D/A-converter

Best internet resources on data converter basics?

Converter Passion will try to plant some seeds of data converter knowledge


Hi all, and my sincere apologies for not posting for a while. I’ve had some rather intense family emergencies that kept me out of the blogosphere for a few months. Slightly wiser from the experience, I want to be careful to not promise too much in terms of blog activity, but the current plan is to resurface more seriously after the upcoming holidays and the New Year.

One of the activities I’ve planned is to list useful data converter resources on the web. First out could be recommended literature for those wanting to catch up on the basics [whatever that may be]. I’ve been contemplating making these lists for some time now, but was re-inspired by the app note/report A Glossary of Analog-to-Digital Specifications and Performance Characteristics highlighted in a recent TI newsletter. It doesn’t have to be just app notes, but it should be resources that are completely open and freely available – preferably without any registration procedures. So please e-mail me, or post a comment here with your suggestions for the best internet resources for anyone new to the field.

Being a bit old-school, I still do read books ;-) so a parallel activity will be to compile a list of good books on data conversion, data converter design & application and related topics – from entry level to the most advanced treatment. Please tell me which books you’d like to recommend, and if you feel like it you can also provide a brief review of 2–200 words describing what you like about it.

As always: Don’t be shy to promote your own work, your company or any one else you wish to give your unreserved praise. All the readers of Converter Passion are of the generous, happy type (I hope). And if you happen to have a data converter book coming out soon, let us know about it too. I’ll be more than happy to highlight it, and if you send me a copy of the final product I’ll also read it and post a book review here on the blog.

Good to see you all again …

Back from IWADC 2011

Views from Orvieto (click to enlarge)

I’m completely in love with Italy now. It was my first time there, and I was impressed by just about every aspect of the visit – the beautiful landscape, the fascinating history embodied in ancient buildings, and of course by the people. Perhaps it was accentuated by me going through the “vanilla phase” with Italy, but it did seem very easy to get a kind smile from just about any Italian I met throughout the entire trip.

A fraction of the big happy family of IWADC delegates

Attending IWADC 2011 was every bit as pleasant: The conference itself ran like clockwork, the medieval city of Orvieto was a decidedly pretty conference location, and the relatively small size of the conference contributed to the relaxed and friendly character of the event. Almost like a family event – a big happy Italian family, I could imagine :-) . The feeling of being welcome and surrounded by “family” was very much accentuated by the hospitality shown by the conference general chair, professor Paolo Carbone (University of Perugia), members of the organizing committee, and other delegates. During the conference dinner when we were also treated with one tasty Italian dish after another, I remember uttering something like “all conferences should be in Italy”. That’s how good it felt to be there.

Who doesn't love Italian food? I was late to some sessions because I tried to eat all the Salatini before they cleared the tables ...

CWCP winner

A winner: Yu Lin

Now being a solid tradition, each conference I attend needs to have an opportunity to connect with Converter Passion. To motivate conference delegates to not be shy we came up with the Connect with Converter Passion (CWCP) prize. The rules are simple: First blog reader to find me at the conference and claim the prize is the winner, and for IWADC 2011 the winner is Yu Lin, a PhD student at Technical University of Eindhoven who was also presenting the paper “An Input Signal Statistics Aware Design Approach and Examples for Analog-to-Digital Converters for communication systems” at the conference [co-authors: Kostas Doris (NXP), Hans Hegt and Arthur van Roermund (TU Eindhoven)]. It was a pleasure to meet such a motivated blog reader. Yu aimed for victory and did not hesitate to claim the prize already at the informal pre-conference reception at restaurant Maurizio. Definitely the right spirit and a worthy winner indeed. Congratulations! Normally, the competition is only for the glory, but this time a small surprise memento was added in the form of a handmade key ring in black leather produced by “Boothill Bob” from Boothill Bob Holsters.

The conference

IWADC covers ADC modeling, testing and data converter analysis and design. Because it is an IMEKO conference, various aspects of measurement becomes a natural thread in many contributions, although the scope is rather wide. It includes calibration of ADCs and error correction of the ADC output, such as presented in the papers “Digital background calibration of subsampling time-interleaved ADCs” by Centurelli from Università di Roma la Sapienza, and “A Linearization Strategy for Undersampling Analog-to-Digital Converters” by Vallant from Cassidian Electronics. Time-to-Digital Converters (TDC) seems to be a growing field, and a fair number of papers addressed various aspects of TDCs, for example “Modeling Noise Effects in Time-to-Digital Converters” by Napolitano, University of Perugia, and “Time-to-Digital Converter (TDC) with Sub-ps-Level Resolution using Current DAC and Digitally Controllable Load Capacitor ” by Alahdab from University of Oulu. There were classic ADC implementation papers such as “A 6-bit 3GS/s Flash ADC in Bipolar 0.25 um for the radiotelescope SKA” by Da Silva from Station de Radioastronomie de Nançay, and I personally found it interesting to hear about ADC implementations in emerging materials, as in “ADC Design in Organic Thin-Film Electronics Technology on Plastic Foil” by Marien of K. U. Leuven.

Scientific discussions

Of my own contributions, the first (An empirical approach to finding energy efficient ADC architectures) was about using the measured performance of chips made by others to better optimize your own design, and the second (Using Figures-of-Merit to Evaluate Measured A/D-Converter Performance) treated how to assess the quality of figures-of-merit often used to make comparisons of measured performance.

IWADC face recognition

There were many more papers presented at the conference, but I don’t intend to walk you through the entire program. Note also that I have mostly mentioned the first authors above although most papers have one or more co-authors. Please add comments below and tell us about any papers, co-authors or delegates that you wish to mention. Or just say hi, and let everybody know you were there too. Share the name of your contribution, and your impressions from the conference with us.

Yes, I was there. Here together with publication chair, Dr. Antonio Moschitta (left) and general chair, professor Paolo Carbone (right).

To round it off, I’ve made a pie chart of the distribution of delegates between countries, based on statistics provided by professor Carbone. As could be expected, the Italian representation was strong. The rest of the countries are quite evenly represented. As you can see, delegates came from both USA and China, although the vast majority were from European countries.

Distribution of IWADC 2011 delegates by country

Please post your comments below if there is anything you’d like to add about the conference.

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: Why is the data converter market dominated by six US companies?

Who’s making a splash in the data converter market?

The Q&A section on this blog might not be too visible, but as you can see here, it actually works: steve asks this interesting question:

Why the $3B data converter market is dominated by the six US companies: ADI, TI, Maxim, LinearTech, National Semi and Intersil. Have any one heard of any data converter companies out of the US?

… and I felt it deserved a dedicated post where you can all have your say. So, what do you all think? And what other companies have you heard of? Do you even agree with steve that it is these six that dominate? If not, who are?

Edit: I’ll be working on the list(s) below, trying to get it as complete as I possibly can. With your help it should work. Just keep suggesting data converter companies to add here. My proposal is to limit the list to companies that provide stand-alone data converters and/or data converter IP. Companies providing data-converter related design services and expert consulting could of course be interesting too, and perhaps go into a second list. [That way I can include my own company, ADMS Design too ;-) ]

Edit 2011-04-09: As you might have heard, Texas Instruments is to acquire National Semiconductor. Read more about it here.

And then there were only five … ;-)

The “Big Six”

As the question was asked by steve, we get the following list of six US data converter companies – dubbed the “Big Six” by jjwikner below – that (supposedly) dominate the ADC and DAC market. Here in alphabetical order:

The list is not written in stone. Have your say below. Should it be the big 3, 4, 5, 7 instead? How about data converter IP dominance – is that a completely different list of companies? And don’t forget the original question: why are all of these companies US-based? Something in the US water? Engineering tradition? Business culture? Choice of target applications? Are the leading Asian companies keeping their designs for in-house use, or did they simply bypass the stand-alone converter phase altogether? Are they now positioning themselves for the inevitable embedded data converter era by developing IP blocks for SoC designs?

The complete list?

To the best of my knowledge, and with the kind help of my blog readers, this is the “complete list” (*) of companies offering data converter IP or stand-alone parts. Again, in alphabetical order, and with the Big Six included:

(*) Allow the list a reasonable settling time constant, and please send me an email or post a comment below if you know of any company not included in the list, or have any other remarks.

NB: I have not necessarily made an assessment of the individual companies included in the list, and the list is therefore no statement of the quality or suitability of the products/IP offered for a particular purpose, nor an endorsement of the company itself.

The list seems very US and Euro-centric, but that’s my current horizon. I’m sure there must be some Asian companies out there. Scientific activity actually suggests that Asia is going to take over this business eventually. So, please enlighten me! Where are those Asian companies?

2011 IMEKO IWADC & IEEE ADC Forum

I recently rediscovered an old friend of mine – the IMEKO International Workshop on ADC, and I though it might be of interest to my blog readers to hear about this conference. It is purely data-converter oriented, so it certainly fits the profile for many of you. The official name I believe is 2011 IMEKO IWADC & IEEE 2011 ADC Forum, where IWADC stands for International Workshop on ADC Modeling, Testing and Data Converter Analysis and Design. It certainly sounds like my cup of tea.

–”Rediscovered“?

Well, … I’ve been aware of this conference for many years. Also, when scanning for source data to include in my large ADC performance survey, previous contributions to this conference would regularly show up on my radar because of their ADC relevance. What I mean is that I haven’t been to this conference for a long time now, but hopefully 2011 will be the year to correct that.

IWADC covers a broad range of data-converter topics – from design to modeling, measurement and error-correction. Check out the official call for papers for more information.

For someone like myself, who is interested in various aspects of data-converters, including characterization, modeling and error-correction techniques, this conference appears to be spot-on. I certainly hope to be able to go there this summer. If you’re anything like me, it’ll probably be worth a few clicks on the official site to see for yourself if you should go there too. Note that it is still possible to submit work! Deadline extended until Jan 15, 2011. I boldly promote this opportunity since, if I’m going there myself I obviously want as many as possible of my blog readers to be there too. A big happy family :-)

In the event that I will actually contribute something, you are sure to hear about it right here on blog. In the meantime, just take a look at the venue and imagine yourself in the medieval town of Orvieto, Italy, 30 June to 1 July next summer … surrounded by like-minded data-converter enthusiasts and the various treasures of the Italian region of Umbria.

Sounds good, doesn’t it?