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Analog Dialogue

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MEMS accelerometers have finally reached a point where they are able to measure vibration on a broad set of machine platforms.  As a result, many CBM system architects, developers, and even their customers are giving consideration to these types of sensors for the first time. Quite often, they are faced with the problem of quickly learning how to evaluate the capability of MEMS accelerometers to measure the most important vibration attributes on their machine platforms. This might seem difficult at first, as MEMS accelerometer data sheets often express the most important performance attributes in terms that these developers may not familiar with. Fortunately, there are some simple techniques for making this translation from acceleration to velocity and for estimating the influence that key accelerometer behaviors (frequency response, measurement range, noise density) will have on important system-level criteria (bandwidth, flatness, peak vibration, resolution).  Check out this article to learn how to express the capability of a MEMS accelerometer in the manner that the following graphic supports (velocity vs. frequency).

 

 

Click here to access this article and please do leave your feedback in this forum!

Thank you!

NevadaMark

With high sample rates (in the GSPS realm) also come a huge payload of data (bits per second). In order to transfer this huge payload, the JESD204B high speed data transmission protocol was adopted. The JESD204B is a high speed, data transmission protocol that employs 8b/10b encoding and scrambling among other features aimed at providing adequate signal integrity.

 

With the JESD204B comes a big alphabet soup which at the outset sounds utterly complicated (which in a way it is). The addition of digital processing blocks such as digital down converters also adds to this confusion. In order to mitigate this confusion and to make the implementation easier to understand, the concept of virtual converters has been introduced. 

Read about it here : Presto! Double Your Number of ADC Channels | Analog Devices 

 

So, when all of a sudden you see "four" virtual converters on a dual-channel ADC, you now know why.... 

 

Cheers

Umesh

Since 1967, the United States has seen 10 presidents. The UN has appointed eight secretaries-general. And Analog Dialogue has had five editors. The most recent, Bernhard Siegel, took the helm of the longest published corporate technical journal in March. He also took some time to share some of his background with Analog Dialogue readers.

 

You’ve held a number of positions at Analog Devices, what motivated you to become the editor of Analog Dialogue?

I’ve always been a big fan of Analog Dialogue. I’ve seen it through a good part of its history. Now, to become the editor is an honor, especially when you consider that there have been only four editors before me. I’ve always appreciated that Analog Dialogue is a technical journal written by engineers for engineers, explaining a variety of applications, products, and solutions always with a focus on innovative technology.

 

I’ve worked in a number of areas in the company, so I’ve been able to see the variety of products Analog Devices offers. As the editor of Analog Dialogue, I have the opportunity and privilege each month to share information about our products and markets with so many of our customers. I cannot think of a better role for me.

 

What is your vision for Analog Dialogue going forward?

Analog Dialogue is about to celebrate its 50th anniversary. My vision is to prepare the journal for its next 50 years. Having said this seems simple, but there are some really big challenges. How our readers get their information has changed. Having immediate access online is critical. Being able to easily search on a subject and have the results right at your fingertips will be one of the key demands from students, educators, and professional engineers. At the same time, I believe there will be a need to maintain a solid and comprehensive source for analog signal processing and design. I’d like to see Analog Dialogue as a leading resource in that area.

 

You’re also a musician. Do you see any parallels between being and engineer and being a musician? Does one help with the other?

Music helps me to relax, but at the same time it is a challenge to perform at the highest level possible. As a musician in an orchestra, you want to play your best as an individual, but you also want to play in a way that makes the whole orchestra sound its best. It’s much the same for me as an engineer. I want to do my best to provide a specific part of a complex solution, but I want to be able to do it in a way that makes the overall solution the best it can be for the customer.

 

What type of music do you enjoy? Any favorite bands or performers?

I enjoy two different band styles – symphonic orchestra with the Kolpingkapelle Mering. We have a great event in my home town called Opera Gala with two great soloists that will be taking place in July. I also enjoy the Brass Band Munich. You can see an example here.

 

I have the honor to play in a semi-professional band conducted by Ekkehard Hauenstein. And we are available to play if you’d like to hire us. Feel free to send me an email.

 

What instrument do you play?

My instrument is the euphonium. One of the best euphonium players in the world is Steven Mead. You can listen to the instrument and how he performs here. I have the same instrument, but of course I’m far from this perfect performance.

 

What do you see as some of the exciting areas in circuit design and how will Analog Dialogue be a part of that?

I’ve been with Analog Devices for 28 years and what is exciting to me is that you can always be sure that the newest technology or next innovation is just around the corner.

 

When I started, 12-Bit ADCs were the best in class ADCs. We are now at 32-bit resolution. Some other breakthrough technologies that we’ll be talking about in Analog Dialogue are: MEMS, Iso Couplers, A2B, DSPs, SDR, and the latest MEMS switch from (real DC) to 6-GHz switching rate.

 

I just read an article about the technology imagined in the Star Trek TV shows and movies. Some of what was science fiction then is becoming a reality now. The scanner Dr. McCoy used to scan foreign materials seems pretty similar to the Consumer Physics SCIO which uses Analog Devices technology. You wave it over food and you can find out how much sugar, how many calories and fat, and other information.  

 

Also, advances in healthcare monitoring, autonomous vehicles, and the IoT—those are all areas where Analog Devices and Analog Dialogue will be playing a role.

 

Do you have a favorite movie, TV show, book, sports team? Is there something about you that you’d like the readers of Analog Dialogue to know more about?

As I am from Munich, needless to say the FCB Bayern Munich is my favorite football team. Let’s see how far they go this year in the Champion League and if they can beat Madrid or Barca.

 

My hometown club is the FCA (soccer Augsburg). They lost the last game against FCB 0:6 and are close to dropping to the secondary league. Fingers crossed.

 

As for TV, pretty much everything to do with space: Star Trek, Star Wars, Stargate, Stargate Atlantic, and Deep Space Nine.  By the way, the film music is great to listen to as well.  

 

And books? Well, I live in Bavaria – one of the nicest areas in Germany. There is a local krimi series called Kluftinger that I enjoy reading when I’m relaxing in our garden.

 

Our thanks to Bernhard for sharing this with us. If you have a question for Bernhard, feel free to send him an email.

 

Photo: Augsburger Allgemeine

 

 

   SAR ADCs can pose unique design challenges to the circuitry surrounding the SAR ADC.  To help our customers, ADI has developed an innovative data acquisition sub-system solution, the ADAQ7980, to overcome these challenges, while also reducing the area of the signal chain, reducing component count, and improving time to market. Its combination of performance, small size, and low power consumption sets a new industry benchmark for high precision data acquisition solutions. This new device has eliminated many of the design challenges that have traditionally been associated with SAR ADC based signal chains, such as the difficulty of driving switched capacitor inputs.  This new converter family reduces design risk and complexity, while also significantly reducing the time it takes to design and evaluate hardware.

 

   The ADAQ7980 product family combines four common signal processing and conditioning blocks to support a variety of applications. As well, the device contains the most critical passive components, simplifying the design process compared to conventional signal chains that utilize SAR ADCs. All active components in the circuit are designed by Analog Devices including a high accuracy, low power, 16-bit SAR ADC, a low power, high bandwidth, high input impedance ADC driver, a low power, stable reference buffer, along with an efficient power management block. Housed within a small footprint 5x4 mm LGA package, the system will simplify the design process for data acquisition systems.

Learn more in "Improving Precision Data Acquisition Signal Chain Density Using SiP Technology" as published in the January 2017 issue of Analog Dialogue.

 

-- Ryan Curran

We in the analog world tend to think of the analog-digital converter (ADC) as the most technically challenging and bizarre animal to deal with. This is actually true to a certain extent. By virtue of the fact that the ADC "straddles" the analog and the digital worlds, there are design trade-offs and decisions made to keep the digital gremlins from making a mess of the analog meal (signal). 

 

Given these complexities and other intricacies, I still have to say that ADCs have become pretty easy and "plug and play" to implement. However, there are situations where the ADC could stop working, or behave erratically. In these situations, it is quite normal to "expect the worst" scenario and start worrying about more complicated stuff within the ADC. 

 

However, in these scenarios, I have come to agree with the theory of Occam's razor where the simplest theory might explain the ADC's behavior. This RAQ discusses exactly that. 

 

Umesh

Welcome to the new Analog Dialogue! Thank you to all the readers who responded to our survey when we began this project over a year ago. You have helped us create a new experience, while staying true to the technical roots of the publication. We have added many new features and given it a new, which we hope you’ll find more engaging and easier to navigate. The new design preserves the integrity of the nearly 50-year-old journal, and evolves the presentation of its contents into a more dynamic and interactive experience for the reader. New features include: cover art of every journal in the archives section, compelling imagery to showcase each article, and plenty of easy ways to share articles in social media. Also, in the near future, it will include ways to add comments on articles, show trending content, and make the overall experience more specific to your needs and interests, through personalization. And we’re expanding Analog Dialogue’s scope in other ways, an example being a new section called StudentZone, a place for engineering students to find articles and resources aimed at solving or assisting with their particular problems and issues. I think you’ll agree that the new format presents a much more contemporary look, more intuitive navigation, and a more responsive website experience, and it’s all easily accessible on your smartphone, tablet, and PC. Of course, print-friendly PDFs of each article are also available.

 

If you can get past being dazzled by our new look, the feature article Improper Power Sequencing in Op Amps: Analyzing the Risks by David Guo sequence is about as “real world” as it gets. Guo takes a look at situations that occur with sequencing multiple supply voltages, in which the power supplies need to be, but aren’t always, established simultaneously with or before any input signals are applied. When proper sequencing doesn’t happen, which is a common issue, overvoltage and latch-up conditions can occur—this article provides some serious help for this tricky design situation.

 

Our second feature, Complete Gas Sensor Circuit using Nondispersive Infrared (NDIR) by Robert Lee and Walt Kester, provides a useful gas concentration circuit design based on the NDIR principle. Note that this circuit board is designed using an Arduino shield form factor and interfaces to our EVAL-ADICUP360 Arduino-compatible platform board.

 

To borrow a line from Bob Pease, “What’s all this Arduino stuff anyhow?”

 

As most of our readership probably knows, the Arduino is an open-source electronics development platform for fast prototyping, with a rabid worldwide support network that’s connected to the Maker movement. It’s credited with boosting interest in electronics lately. The Arduino is easy to interface to and easy to control from a PC. The platform was originally aimed at students with no background in programming or electronics. Hobbyists, artists, and students of all types, use Arduino to create all kinds of projects. It very much simplifies the process of working with microcontrollers, and the programming is also simplified. However, a recent article in ElectronicsWeekly.com says that the latest, more powerful, Arduino configurations are being used more and more in professional engineering to fast-track prototypes, especially for the Internet of Things (IoT). Analog Devices joined the Arduino bandwagon a few years back, when we realized that both hobbyists and professionals were using the platform. Our Arduino-compatible platform board was the first to incorporate dual high-performance ADCs.

 

To our readers, thank you for your loyalty, support and feedback over these many years. We hope you enjoy the Analog Dialogue redesign and we look forward to continuing our analog (and mixed signal, and digital, and whatever the future may bring…) dialogue!

 

Best regards,

Jim Surber, Editor

Historically, the Superheterodyne receiver has been the go-to system architecture for many aerospace and defense wireless radio applications where high performance is of the utmost importance. However, the Superhet is costly in terms of design time, components cost, and SWaP (size, weight, and power), leaving many system designers looking for alternative radio architectures such as the Direct Conversion architecture. As aerospace and defense system designers continue to work towards reducing the SWaP of their wireless radio systems, they continue to discover and take advantage of ADI’s integrated transceiver technology as a means to do so.

The AD9361 integrated transceiver has already made a significant impact in many military radio systems where low power is key, and now with the release of the higher performance/bandwidth AD9371, ADI’s transceiver technology is being designed into all types of aerospace and defense applications- from portable soldier radios to high performance radar systems. Wyatt Taylor and I discuss this trend in our paper “RF Transceivers Provide Breakthrough SWaP Solutions for Aerospace and Defense”, which you can read in this month's issue of Analog Dialogue.

http://www.analog.com/library/AnalogDialogue/archives/50-09/rf-transceivers.html

September means the fall is rapidly approaching in my part of the United States, and that means (finally) crisper temperatures, colorful leaves, and bright clear days. Of course, our Analog Dialogue readers are spread out all over the world, so September may mean something completely different to you. Wherever you are, we’re glad you’re tuning in to our magazine and hope it provides you with timely information and design ideas and solutions that you can put to work. We love feedback, so please take a moment—if you ever have one free—and let us know how we’re doing or what you’d like from Analog Dialogue. Incidentally, the Analog Dialogue Facebook page is a great place for that.

 

The technical focus of this issue of Analog Dialogue is ADI’s recently announced RadioVerse highly-integrated wideband transceiver technology and radio design ecosystem. This groundbreaking, game-changing, RF-to-baseband signal chain on a chip, accompanied by an expanded solution-based design environment, redefines radio design at the circuit, architecture, system, and software levels. From idea, to proof of concept, to production—all at light speed, as its motto proclaims. You can’t get much faster than that. There’s so much flexibility, versatility, and technology going on with RadioVerse transceiver solutions that I can’t do it justice in my limited space here. But I’ll let our feature article authors tell you some of the technical details.

 

Brad Brannon focuses on the state-of-the-art in Zero IF (ZIF) transceiver architecture, which is a key enabler in the RadioVerse portfolio of transceiver ICs. Brad explains how the architecture is the optimal solution for high-performance software-defined radio signal chain integration, but that certain limitations had to be overcome in order to meet the performance, agility, and flexibility demanded by high-end wideband wireless applications. Those limitations have been solved through innovation and Brad provides the performance data to prove it.

 

And in the second feature, Wyatt Taylor and David Brown examine how the RadioVerse transceiver solution portfolio enables Size, Weight and Power (SWaP) reduction in many military applications. Doing more with less is a mandate in military system design these days and SWaP is a key requirement. In the authors’ words, “The next generation aerospace and defense platforms are demanding a new approach to RF design, one where several square inches of an existing platform are integrated into a single device. Where the boundary between software and hardware is blurred.” RadioVerse single-chip wideband RF transceivers were expressly designed to support this industry trend; read how they are enabling next-generation military applications.

 

After reading these articles I think you’ll agree that RadioVerse represents a giant leap forward for the analog portion of high-performance wireless communications system design, and in the realization of highly flexible software-defined radio architectures. To get the full story, visit the RadioVerse pavilion page and then, imagine the possibilities.

When tasked with designing a circuit that measures current, we are often presented with numerous options, circuit topologies and devices. Selecting the most appropriate circuit and amplifier for the job depends on several factors, so it is useful to begin listing some of the options available and work it out from there.

 

Learn more in "Common Sense for Current Sensing" as published in the September 2016 issue of Analog Dialogue.

 

murphy

 

 

We welcome your feedback in the comments section. Has this article been useful or helped you in your design? Would you like more information on this topic?

 

Best regards,

Gustavo Castro

I'm selecting an op amp for a high-precision signal path and need to choose the best gain-bandwidth product. Isn't faster always better?

 

Determining which op amp has the right gain-bandwidth product for our application is like Goldilocks choosing which bowl of porridge to eat. We want to choose one that is not too fast and not too slow but gives us just the right trade-offs between speed, accuracy, and stability.

August RAQ Goldilocks.jpg

For a closer look at these considerations, see "Choosing a Precision Op Amp? Trust Goldilocks" in the August 2016 issue of Analog Dialogue.

 

We welcome your feedback. What other topics would you like us to discuss? Are you interested in more information?

 

Best regards,
Daniel Burton

August always makes me a little anxious—I think it’s a flashback from school days: summer’s almost over and it will soon be time to hit the books. That got me thinking about today’s electrical/electronics engineering students. I’ve heard comments and opinions about how engineering students aren’t interested in analog design anymore, and how schools don’t teach the analog/linear fundamentals like they used to.

 

I did an informal online survey of the curricula at a number of the major engineering schools in the US, and it sure looks like analog/mixed signal engineering is alive and well there. Stanford has the Murmann Mixed-Signal Group, innovating analog-to-digital interface circuits. From the photo on their site, it looks like they have a healthy group of grad students. Texas is apparently a hotbed of analog design learning and research, with the Texas Analog Center of Excellence at the University of Texas, Dallas. They claim to be “the largest international, university-based analog technology center,” creating design innovations to improve health care, energy efficiency, and public safety. About 200 miles to the south, Texas A&M has their Analog and Mixed-Signal Center, for “the education and training of highly qualified engineers for design and manufacturability of analog and mixed-signal integrated systems.” And of course MIT weighs in. According to the online description of their EE curriculum, “a focus is digital and analog signal processing with emphasis on design and practical implementation.” All of the university curricula I looked at—and it was a lot of them—still have the  analog/linear circuit fundamentals, along with numerous specialized analog/mixed-signal design courses at both the undergrad and graduate levels. I found that reassuring. We here at Analog Devices know that analog technology is a flourishing, vital, and exciting field—we just need to make sure that fact is communicated to today’s students. Attention EE students: analog rocks!

 

Speaking of state-of-the-art analog electronics, the article in this month’s issue by Umesh Jayahoman explains how the high bandwidth sampling core and the digital downconverter options contained in the new generation of RF ADCs (aka GSPS ADCs) enable design innovation in communications infrastructure. This mixed-signal technology offers a flexible pathway to rethink and redefine the radio architectures that will cater to the growing demands of consumers. The Capacitive Programmable-Gain Amplifier device is the subject of the second article by Miguel Usach and Gerard Mora. Our two engineers provide a look into the circuit architecture, describe the amplifier’s advantages in certain applications over the resistive PGA, and compare some of the critical specifications of the two amplifier topologies. Daniel Burton tells us we "must trust Goldilocks" when choosing a precision op amp in his RAQ article. You can read it all here.

 

So happy reading and please enjoy the rest of your summer, and if you’re an EE student, get ready to dive into those (hopefully) analog and mixed-signal design courses. The real world anxiously awaits your innovation.

 

In order to fill the needs of many customers today the sample rate of our ADCs at ADI is getting pushed higher and higher.  Customers desire to sample frequencies in the GHz range which comes with a stiff penalty of higher bandwidth in the digital data transmission.  High frequency is needed but typically not high bandwidth.  Generally about 100-200MHz at most is required but the operating frequency may be up at 1.5 GHz or higher.  Here come DDCs to the rescue.  With a DDC, input frequencies in the GHz range can be sampled by the ADC and then tuned and filtered by the DDC to select the 100-200MHz of required bandwidth.  This allows the digital output bandwidth to be reduced to a manageable level resulting in less challenging layout and cheaper FPGAs.  This all sounds great, but how does this DDC actually work.  Take a look at my latest article on Analog Dialogue titled "What's Up with Digital Downconverters Part 1" to learn more.  You can find it here: http://www.analog.com/library/analogdialogue/archives/50-07/digital-downconverters-part-1.html.

Stay tuned for the second part of the article coming up in Analog Dialogue in November of this year.  I welcome any feedback and questions you may have.

Welcome to the exciting new frontiers in high-performance data conversion: GHz bandwidths, giga-samples-per-second, and direct RF conversion. As CMOS process technology has advanced, speeds have increased and the addition of signal processing to data converters has become commonplace. The lines continue to blur between analog and digital as the trend toward software-defined systems and broad-band signal conversion grows. Our two  feature articles this month both deal with design details of ADI’s latest RF data converters. These blazingly fast embodiments of devices that used to be considered mostly analog now incorporate just as much digital functionality. In fact, these devices, with output data that is processor-ready, are more like  integrated data conversion systems than components.

 

Jonathan Harris provides an in-depth look at the digital down conversion function in a couple of ADI’s high-speed ADC devices. This digital signal processing function obviates the need to implement multiple analog down conversion stages in a GHz RF signal chain, and it has the added advantage of improving dynamic range within selected bands. This article explains the signal-tone flow through a DDC block and introduces an online Frequency Folding Tool that aids in the analysis of the sampled spectrum.

 

The second article addresses the transmit side of the radio  signal chain. Dan Fague describes how a new breed of RF DAC can directly synthesize GHz signals, eliminating the need for entire stages of analog frequency upconversion, thus simplifying frequency planning, and reducing power consumption and the size of the radio. Advancements in CMOS process, innovations in DAC architectures, and implementation of JESD204B serial interface, have come  together to enable a practical high-performance GHz DAC. Dan explores the  functionality and performance of this remarkable product.

 

With more and more digital processing and frequency translation being done inside the direct RF data converter solution itself, and the output data seamlessly interfacing to an FPGA, the radio system designer’s IP can largely reside in the digital domain. This  unprecedented flexibility in system  architecture is helping designers reach the next level in truly software-defined radio platforms. All of which enables many innovative applications that couldn’t have been considered even a few years ago. Or as we like to say around here, “Ahead of what’s possible.”

Last month, a horse named Nyquist won the 142nd Kentucky Derby. Of course, I immediately thought of the groundbreaking engineer and communications theorist Harry Nyquist, whose work is fundamental to data conversion
applications. He’s a true engineering celebrity of the sort that I wrote aboutin an earlier Editor’s Note. It was a thrill to see the name of one of our engineering heroes being honored in the mainstream international media.

 

Harry Nyquist came to the US from Sweden in 1907 at the age of 18, and promptly earned BSEE and MSEE degrees from the University of North Dakota and then a Ph.D. in physics from Yale. He went on to do amazing things at AT&T and Bell Labs, and his name lives on today most notably  in the Nyquist sampling theorem, also known as the Nyquist–Shannon sampling theorem. So when I saw the horse Nyquist, my mind immediately started to think up engineering jokes: I wonder if Nyquist will run twice as fast as the next fastest horse…How do we know that the horse we see is real and not an aliased image…Will his lane at the starting gate be the Nyquist Zone?  Then I discovered Nyquist the horse is actually named for a hockey player. My short-lived excitement was crushed.

 

In this issue, our feature article authors Colm Slattery and Ke Li take a look at a particularly timely issue, as more and more environmental regulations to control and monitor liquid waste are appearing worldwide.  Electromagnetic flow technology is the choice for this particular application, and the trend is toward an oversampled approach, which challenges the ADC requirements. In addition to oversampling design considerations, their detailed article discusses the significant power
challenges involved in the application.

 

Update:
In the 141st running of the Preakness, Nyquist came in third, so no Triple Crown bid for this horse. But those of you involved with  mixed-signal system design, know that Nyquist, the sampling theorem, can never really be beaten. It is also known to occasionally bite you.

 

The data sheet for the amplifier that I've chosen for my application specifies a small signal bandwidth along with a large signal bandwidth, and they are quite different specs. How do I determine if my signal qualifies as small or large?

 

Whether you consider your signal small or large, proper selection of an amplifier requires (among other things) knowledge of how fast it needs to be. And the larger the signal at the output, the harder it gets a good, high-fidelity reproduction of the input signal.

 

Learn more in "Citius, Altius, Fortius" as published in the April 2016 issue of Analog Dialogue.

 

April-RAQ-Illustration.jpg

 

We welcome your feedback in the comments section. Has this article been useful or helped you in your design? Would you like more information on this topic?

 

Best regards,

Gustavo Castro