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Are the Terms ‘Integrated’ & ‘Monolithic’ Synonymous?

Last month, in response to my post The Other Side of the Integration Coin, reader TheMeasurementBlues asked if we could consider discrete op-amp or data converter devices as opposed to ICs. My first response was to consider the question from the manufacturer’s perspective. From this view, I asserted that “vendors design, verify, fabricate, and package these devices as they do more complex ICs. In that regard, they are subject to the same kinds of challenges and benefit from the same kinds of advancements as do more complex analog and mixed-signal blocks.”

Looking at the same question from the system designer’s perspective, I came to the same conclusion but for a completely different reason: “Integrated devices,” I wrote, “provide barriers of abstraction that relieve designers from a great deal of technical detail compared to discrete designs. This changes the way we design with integrated functional blocks, be they as conceptually simple as an op amp or as complex as a complete AFE.”

Throughout this discussion and, indeed, its precursors, the assumption I had made was that our conversations about integrated circuits were inherently about monolithic devices — that the terms “integrated” and “monolithic” are essentially synonymous. A recent product announcement, however, has made me question that assumption.

One of the many new-product announcements at APEC (the Applied Power-Electronics Conference and Exposition) this year was one from Vicor, which introduced a new packaging technology that the company has dubbed “Converter housed in Package” or ChiP technology. According to Vicor VI chip product line vice president Stephen Oliver, the company is making available devices that exploit this packaging technology in sizes ranging from 1323 (13 x 23mm) to 6123 (61 x 23mm). These are not the smallest set of footprints in the power converter market, but impressive when coupled with their high-power densities (up to 3kW/in3 ), high-area densities (up to 850W/in2 ), and efficiencies (up to 98%).

The packages can house a variety of complex power-management functions including AC-DC conversion with PFC (power-factor correction); isolated and non-isolated DC-DC conversion; buck, boost, and buck-boost regulation; and PoL current multiplication. Devices in the ChiP form factors can include microcontrollers with the power train to implement factory- and user-defined functions, command sets, and telemetry capabilities.

Like large ICs, members of the ChiP family can take advantage of several cooling methods depending on their worst-case operational dissipation and the system’s thermal design: These include direct single- or dual-side cooling plus thermal conduction through the leads, cold-plate cooling, or cooling with standardized finned heatsinks.

Clearly, these are not monolithic devices. At minimum they contain a power-train silicon and off-chip passives — notably magnetics. In their larger forms, they might contain a controller IC, MOS switches, passives, and logic silicon.

But from a system-designer’s perspective, do I care how many individual devices the package contains, or am I more interested in the nature of the package as a unit object? Assuming that commercially available products — be they monolithic or otherwise — provide adequate reliability, more and more I’m thinking that I’m interested in the package as a unit object: It embodies a great deal of engineering value and provides a barrier of abstraction that relieves me from a great deal of technical detail compared to a discrete design. And that, recall, is a key attribute of integrated circuits.

What do you think? What attributes are defining when we refer to integration? Is it monolithicness [sic]? Or does the barrier of abstraction prevail and, in so doing, relieve us from needing to know about the underlying implementation? In an age when modular components and monolithic ICs may overlap in footprint, mounting method, cooling method, design-in procedure, and evaluation process, is there a distinction in the difference?

8 comments on “Are the Terms ‘Integrated’ & ‘Monolithic’ Synonymous?

  1. Michael Dunn
    March 25, 2013

    Personally speaking, the closer a blackbox is to a circuit module , the less confidence I have in its quality and reiabililty. A monolithic IC must be perfect, right? A hybrid, close to perfect, but some room for error. A module like LTC's micromodules: almost as good. But beyond that, I start to have doubts :-}  Bigger modules often feel to me to be the least reliable part of a system.

  2. Brad Albing
    March 25, 2013

    Hmm… if you did a Failure Mode Effects Analysis on a module, would you treat it as a black box or as a bunch of components? I.e., would you need to go thru all those components and evaluate failure mode results by opening and shorting each component, one at a time? Just wondering….

  3. Michael Dunn
    March 25, 2013

    Hmmm.

    This talk of modules is making me think of the lovely DC-DCs introduced by Rifa (now Ericsson) many years ago. Built using more-or-less standard components, on a ceramic PCB, they claimed an MTBF over 1E6 hours. My, I wanted to use one…

  4. Joshua Israelsohn
    March 25, 2013

    Michael-

    Regarding your lack of confidence in modules:

    I've worked in engineering departments responsible for desigining modules, hybrids, and ICs and my experience has been that the design-quality criteria and design-review processes are equally stringent. In manufacturing, the methods used to derive acceptance criteria and guardbanding are quite similar.

    As far as performance to datasheet specifications is concerned, there is nothing inherent in any of these forms that suggests that one is superior or inferior to the other. Were that not true then, by your logic, truly large system would never work properly yet we use distributed resources on continental-sized networks every day and rarely experience a functional failure.

    Or flip the question around: Do you think that, say, your laptop computer would be more reliable or perform to a higher standard if you replaced all of the modular structures (WiFi radio, memory, PSU) with their constituent components mounted directly to the mother board? I doubt it. I also doubt the result would be affordable.

  5. Joshua Israelsohn
    March 25, 2013

    Brad–

    I think the failure-mode analysis always extends to a level of detail sufficient to establish corrective action by the organization performing the analysis. For example, an IC manufacturer may have to examine not just individual transistors on a die but the individual layers that form the active devices. For a module maker, it may suffice to identify a failed component and determine the cause of failure at a higher level of abstraction (failure due to overstress, for example, being distinguished from, say, a manufacturing or design defect in the component).

     

  6. Michael Dunn
    March 25, 2013

    Of course there's nothing inherent  about modules that makes them less reliable than systems using ICs etc. I was really just describing my gut feeling. I'm happy you've worked in places that treated modules with the same care as ICs, but the fact remains that any joe can build modules in their garage, whereas ICs take a slightly greater commitment.

  7. Michael Dunn
    March 25, 2013

    You're kidding me! :-)))

    On the other hand, you know that LTC or TI part wasn't  designed in a garage, whereas that module from Power-R-Us, well, less certain.

  8. Brad Albing
    March 25, 2013

    OK, so I'm rethinking this idea I had a few days ago about turning some of my guitar widgets into custom ICs.

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