By Cary Chin
My goal this month was to determine the power efficiency of cellular communications on the new iPad—specifically to determine any difference in power efficiency between communications in 4G LTE vs. 3G.

We saw last month that the new 4G LTE data speed was extremely impressive. I’ve now seen speeds of up to 20 Mbps using 4G LTE for both downloads and uploads, many times faster than I’ve seen on 3G networks through any carrier, and even faster than my home internet connection. But there’s usually a price for that level of performance, and the question I’ve been trying to answer is, what is the cost for all that speed in terms of nWh/B (nanoWatt hours per byte)?

While this question seems fairly straightforward to answer, I ran into a number of interesting problems trying to take this month’s measurements. First of all, all the data I’ve taken over the last couple of years depends on running repeatable experiments, and comparing multiple runs to determine the energy usage of controlled variables such as the display, wireless communications, sound, and other areas of interest. My first problem this month as I started to look at 4G LTE communications was that my test vehicle (the 2009 Star Trek movie), is no longer available for streaming via Netflix! Netflix has been having its own problems in the last year and has not renewed agreements with several of its movie content providers, and Star Trek was one of the casualties. Unfortunately for me, that was my standard movie test for gauging energy consumption of movie streaming versus local playing. So my first task was to recreate my testing setup for movie streaming.

After looking at several possibilities including other online content providers, cable options and even home network sharing, I decided to pursue a path using the cloud. My new setup is using Dropbox for cloud storage, and I’ve uploaded several copies of Star Trek with varying resolutions (and file sizes). My locally played version of the movie is 1.96GB, which is too large to stream. In fact, that’s my entire monthly allocation of data! So I’ve created a 1GB version to use as my “high-resolution” version, and several other smaller versions for comparison.

I’ve just started collecting data, but my first data points are already interesting. Recall last month that playing Star Trek (2:06:46) on my new iPad with the display and sound turned all the way down used about 2.1Wh of energy. Turning up the display to maximum brightness increased the energy consumption to a whopping 11.5Wh or around 9.4Wh (or 4.5W) just for the retina display backlighting! Adding sound increased energy consumption to 11.9Wh.

Now with my new streaming setup, streaming my 1GB version of the movie (which looked GREAT by the way) over 4G LTE, energy consumption is up to around 17.4Wh, adding another 5.5Wh of energy for the wireless transfer of the 1GB of data. And that’s just my first data point. We saw previously in experiments on 3G networks that low signal quality could increase energy consumption of the data transfer by 2x-3x. So 5.5Wh of energy for 1GB of data, we now have our first data point on data transfer energy efficiency in 4G LTE. For video streaming, efficiency has come in at 5.5 nWh/B.

While all of the data isn’t in yet, we can see that fast communication does certainly require significant energy. But maybe even more importantly, it’s clear that the latest generation of cellular data communications is another game-changer. Data transfer speed is clearly no longer my biggest problem for wireless communication. The real issue is going to be cost. Current cellular data plans average between $10/GB and $20/GB, so streaming my 1GB version of Star Trek over a cellular network may look great, but the data transfer costs more than buying a ticket to the theatre—well, at least the popcorn is cheaper. The bottlenecks are moving (or maybe just rotating) again!

—Cary Chin is director of marketing for low-power solutions at Synopsys.

By Cary Chin
I had pretty much decided not to purchase the new iPad (aka “iPad 3”) because I don’t use my first two iPads as much as I could. They are just something extra to carry around, and they don’t quite replace a laptop when I need one.

Of the rumored new features on the new iPad (Retina display, A5X processor and quad-core GPU, 5MP iSight camera, and 4G LTE), the only one that seemed significant for my use was the 4G communications, and that wasn’t quite enough to push me into those opening day lines. However, I’ve changed my mind, and am now playing with my new iPad. And the feature that pushed me over the edge only showed up at the last minute on the new feature rumor list—a significantly bigger battery!

Battery capacity and charging mysteries explained
Battery capacity should really be the headline for the new iPad. Battery capacity jumps 70% to a whopping 42.5wH! That’s higher capacity than the 11” MacBook Air. The overall device is only marginally thicker and heavier than the iPad 2, but a 70% increase in battery capacity? The rumors were that Apple had come up with some magical new battery chemistry. Could it be that the rest of the world had fallen that far behind? Well, a closer analysis shows again that there is no magic. The new battery capacity of the iPad is very much in line with the size (and weight) increase of the new battery pack.

The weight of the battery pack has increased 54%, and the total volume of the pack has gone up by 77%, so the 70% increase in capacity is in the right ballpark. The amazing thing is how the overall product is put together with the same length and width dimensions and only a 0.6mm increase in depth, plus about 50 grams in net weight. With a net product-level increase of around 7% in size and weight, battery capacity has increased by 70%. The “magicians” in Cupertino have once again shocked the world with the same technology that everyone else has access to, but they designed it better.

The other chatter on the Internet concerns battery charging. There are many complaints about slow charging of the new iPad. This is no surprise, because while the battery capacity has increased by 70%, the charge rate hasn’t changed. Charging a 42.5Wh battery with a 10W charger will take a theoretical 4.25 hours, assuming 100% efficient charging. In reality, expect five- to six-hour hour charge times. Using a 5W (iPhone) charger or a computer USB port will take additional time, which is inversely proportional to the current supplied by the port. And all of this assumes the iPad is off (or at least not in use) during the charging. The answer to your charging problems: Use the included 10W adapter, and charge overnight.

Retina display—good, bad, but not ugly
It’s good that the battery capacity has increased dramatically, because while the retina display looks great it’s a definite power hog. I ran my baseline “Star Trek” movie test on the new iPad, and basic power efficiency looked pretty good. Playing the entire movie in the “Max Battery” mode (airplane mode on, display and sound at minimum) required just 2.13Wh of energy. That’s even better than the iPad 2 at 2.25Wh. The basic hardware is getting more powerful, but energy efficiency is increasing even faster. Isn’t technology wonderful?

Once the brightness was turned up the display looked fabulous, especially displaying high-resolution pictures and computer-generated graphics. My movie test didn’t look much better on the new iPad vs. my iPad2 though. It’s clear you’ll need higher definition (at least 1080p) video to see much improvement. And the news gets worse.

Given the baseline energy measurement, we can get a pretty good estimate on how much that beautiful display is going to cost in energy. Turning up the brightness to maximum on “Star Trek” increased the energy consumption to 11.48Wh! That means the additional energy needed just to run the display between minimum brightness and maximum brightness is 9.35Wh for the Star Trek movie (2:06:46), and power consumption just for the display is around 4.45 watts. Imagine using a 5W charger to try to charge this device. Turning on the display at max brightness immediately makes it impossible to charge the battery. All of the energy is used up just to keep that display nice and bright. The charging time issues will continue to swirl in the user community for some time, and have a real impact on how the device can be used.

I believe this is a potential design flaw in the new iPad. What’s the point of a big, beautiful Retina display, if practicality forces you to turn down the brightness to the minimum usable level? And we’re just starting to see the other impact of viewing high-resolution video—gobs of data. Getting the most out of the Retina display will put many additional strains on the product, from device storage limitations to the cost of data plans.

From my standpoint, the Retina display, while beautiful, isn’t worth the high energy (and data) cost. I can’t see the individual pixels on the new iPad, but to tell you the truth, I can’t see them iPad 2 either, without high-powered reading glasses. Is it possible that Apple has lost sight of the fundamental design principle that “form follows function”? Knowing what I know now, and had there been the option, I would have ordered a custom new iPad with the old display, and been very happy with the 70% larger battery.

A killer app
While these issues will keep the blogosphere busy, there’s another application of my new iPad that is a clear winner. I got the Verizon 4G LTE iPad, and the communications speed is very impressive. I’m seeing network speeds up to 13 Mbps on LTE, compared to 700 Kbps in 3G. These bracket the network speeds of up to 4 Mbps I get on my iPhone 4S on the AT&T network (you know, the 4G network formerly known as 3G). With much better coverage in my area, Verizon 4GLTE is looking like a winner, and I really can’t wait for the iPhone 5!

On top of that, the Verizon personal hotspot feature is included with the service plan on the iPad, so for the same $20 I used to spend just to enable the personal hotspot on my iPhone, I get expanded coverage across both AT&T (iPhone) and Verizon (iPad) networks—plus a faster network connection to share. And with the iPad’s new larger battery, the killer app for me is using my new iPad as a WiFi hotspot. I was traveling last week, and two of us used the iPad as a WiFi hotspot for more than 12 hours. That’s more than a full day’s work, transferring a total of 297 MB of data in email and Web browsing. At the end of the 12 hours, the battery capacity was still at 57%! That’s incredible! And the irony is that this best and most impressive usage of the new iPad was run with the fancy new Retina display OFF.

Next time, I’ll look at power efficiency of the 4G LTE network vs. 3G. All that speed has got to cost something, right??

–Cary Chin is director of marketing for low-power solutions at Synopsys.

By Cary Chin
Since the release of iOS 5 along with the iPhone 4S back in October, we’ve finally seen the conclusion of ”antennagate” on the iPhone 4, only to be quickly replaced by “batterygate” as the new biggest complaint of iOS 5 users.

I’ve personally experienced some of the problems reported throughout the user community. iPhones and iPads seem to “hang” while trying to connect or communicate, and the result is battery drain of more than 1% per minute (on iPhone 4S), similar to the power used when streaming a video over a weak 3G connection. I’ve seen this problem occur while connected via wifi as well, with a similar—a warm device and a drained battery within an hour or so.

The common denominator seems to be iOS 5.0, which was patched less than a month after its initial release to version 5.0.1. The top billing on that update read, “Fixes bugs affecting battery life.” But my problems haven’t gone away, suggesting that there were quite a few of these “bugs” floating around in the original 5.0 release. I’ve gotten used to powering down my phone occasionally, which for me has been the only consistent way of resetting it deeply enough to correct the problem. I’ve tried to isolate and reproduce the problem, but haven’t had any luck.

Today will be the rumored announcement of the iPad 3, and if you believe the rumor mill, the long awaited iOS 5.1 update, which again is said to fix the “batterygate” problem. As we’ve discussed frequently, the complexity of today’s smartphones is hard to comprehend, especially because the entire hardware platform and software stack continue to evolve and expand rapidly. Identifying these kinds of problems is extremely difficult, but in our new reality of social networking, information from millions of users can be pooled together to help isolate problems as a community. This kind of “social debugging” is fundamentally changing the way we think about software development. And in the grand scheme of things, life is just one big beta test anyway, right?

–Cary Chin is director of technical marketing for low-power solutions at Synopsys.

By Cary Chin
One of the more intriguing smartphone features that hasn’t yet reached the final product is the possibility of a solar cell embedded in the screen that would produce enough energy to power the device indefinitely (at least in the sun).

Rumored via a patent application by Apple several years ago, with a recent prototype by French company Wysips, and even by reclaiming “wasted” light (http://www.phonescoop.com/articles/article.php?a=9703 ) on OLED displays, the days where your smartphone battery needs to be plugged in to be charged may finally be coming to an end. It’s certainly not an unfamiliar scenario. Calculators are just smartphones without the phone and a bunch of other stuff, and they’ve had this mode of operation for more than 30 years.

Current technology is targeting about 30 minutes of talk time in 1 hour of charging, which seems pretty reasonable. Of course, today’s smartphone functions go way beyond just talking on the phone. “Talk time” is dominated by the energy cost of cellular transmission, but the display is typically off and other data functions are inactive. That one hour of charging might translate into 10 minutes of streaming a video, or 5 minutes of interactive online gaming. On today’s iPhone 4S, most usage reports suggest around 9 hours of talk time on the 5300 mWh battery, working out to around 600 mW of power required to operate the phone function. That would put the target at around 300mW for a hypothetical iPhone 4S solar cell, or with the 2”x3” screen size, about 50 mW per square inch.

On a larger scale, I’ve recently installed solar panels on my house, composed of 65”x39” Yingli Solar panels of 235W each, which works out about 105 mW per square inch. I’m a little surprised that the efficiency of the large (inexpensive) panels seems to be twice as high as the target for a compact solar smartphone charger (probably because the panels on my roof are more than two inches thick, or five times as thick as the whole phone), but at least the target doesn’t seem out of reach. In another generation or two, you’ll be able to talk on the phone all day without draining the battery appreciably, assuming you’re not also using the on-the-fly foreign language translation option or grammar correction module at the same time.

So while it seems like we’re still a little ways away from having smartphone-class devices that will power themselves indefinitely, it’s not too early for the entrepreneur’s tip of the month: CLEAR smartphone cases…!

–Cary Chin is director of technical marketing for low-power solutions at Synopsys.

By Cary Chin
Last time we looked at the relative signal strengths on the iPhone 4S vs. the iPhone 4 using field test mode to gather data in a variety of locations around Silicon Valley. The data below shows signal strengths for the 4S and 4, with and without using the “death grip” on the phone.

We saw slightly better reception on the iPhone 4S than on the iPhone 4, but the really dramatic difference was the delta in signal strength with the “death grip” applied. The iPhone 4S showed a signal strength attenuation of around -6dBm which is significant, but the iPhone 4 showed a huge drop of -17dBm, more than enough to cause dropped data and voice connections.

The next question is, what’s the relative performance of the two smart phones in our video streaming test? We’ve run quite a few tests already, so here’s a summary from the archives:

We have a couple of comparable data points. The data suggests that not only does the iPhone 4S fix the death grip problem (from the graph above) as a result of the new dual-antenna design, but it also seems to have markedly better power efficiency in communications. That’s likely due to the new and improved modem chip. Comparing the baseline numbers with the “2 to 3 bar” data, the 4S requires only an additional 500 mWh of energy to stream the movie vs. watching it locally, compared to 1500 mWh on the iPhone 4. That’s a pretty significant improvement. Plus, we don’t see the runaway energy consumption problem at very low signal strengths as was the case in our original iPhone 4 tests. This one’s a little harder to draw a conclusion, since the test conditions don’t match up too well. I’m very interested in looking at iPhone 4S performance on the Star Trek test at the edge of its signal reception capability.

It’s time to go locate another good testing spot, and watch the movie a few more times. I’ll report back next time!

–Cary Chin is director of technical marketing for low-power solutions at Synopsys.

By Cary Chin
One of the areas I’ve been most interested in testing out on the new iPhone 4S is the effectiveness of the new dual antenna design, which is claimed to solve the now-infamous iPhone 4 “death grip” problem. Since we’ve already seen in previous experiments that battery life on these devices is strongly tied to communications and signal strength, any improvement in reception would have a direct impact on battery life whenever the radio is being used extensively. And with the addition of Siri, expanded notifications, and iCloud in iOS 5, it’s clear that the percentage of time our coveted smart phones will be spending connected (or connecting) to data networks is going to be increasing.

To get a picture of the effectiveness of the new antenna setup, I took data using the built-in Field Test mode (key in the string ‘*3001#12345#*’ without the beginning and ending apostrophes into the Phone application and then push “call”), which conveniently displays signal strength in dBm (power ratio in dB referenced to 1 mW). I compared the signal strength on the iPhone 4S with the iPhone 4, and also recorded signal strength for each device while using the “death grip” that Steve Jobs warned us about. It’s not as glamorous as the “Vulcan death grip” that Mr. Spock administered to Captain Kirk in “The Enterprise Incident,” but everyone knows there’s no such thing as a “Vulcan death grip” anyway!

The data chart below shows average signal strength data in 9 different locations, from “terrible signal” (1 bar or less) to “strong signal” (5 bars). Note, as we’ve mentioned before, signal strength for these kinds of transmissions is notoriously flaky. The variance in readings in each location over a period of around two minutes was between -4 dBm and -10 dBm. The “terrible signal” location was in my office in Mountain View. And just for grins, I’ll bet you can’t guess where, within a five-mile radius of Mountain View, you can reliably get a very “strong signal.” If you guessed a street address of “One Infinite Loop,” you’d be correct!

The top line (green) is the data for the new iPhone 4S. It signal reception is generally a couple of dBm better than the original iPhone 4 (orange). This is a measureable difference, but practically not too significant, especially given the large variations in the measurements. However, there is a big difference when comparing the signal strength of the two devices while applying the “death grip” (light green and light orange). The iPhone 4S shows a drop of less than -6 dBm on average using the “death grip”, but the original iPhone 4 shows a whopping drop of over -17 dBm, and that’s conservative because the Field Test numbers were “pegged” at -116 dBm. This would definitely result in dropped calls in any areas without a very strong signal to begin with.

So, the iPhone 4S does indeed solve the “death grip” problem. Its dynamically switching dual-antenna design (one on the bottom and another on top) is an effective solution that we’re sure to see in other smart phones as well. Just for the fun of it, I also applied a “double death grip” to the iPhone 4S, and saw about an additional -6 dBm of signal strength loss as a result. But don’t try this one at home (or at least not in public). It’s legitimately in Apple’s category of “you’re not supposed to hold the phone that way!”

Next time; we’ll try to use the data we’ve gathered to predict and measure the improvement in energy efficiency of the iPhone 4S over the iPhone 4 as a result of the new antenna design. Stay tuned.

–Cary Chin is director of technical marketing for low-power solutions at Synopsys.

By Cary Chin
I’ve had my iPhone 4S for a few weeks now, and have gotten to know it pretty well. Mine is the 64GB model, mostly because I want to play around with the new 1080p video recording capabilities, and don’t want to worry about running out of storage space all the time.

I’ve read many reports online about runaway battery consumption with the new 4S, but I haven’t noticed any huge change vs. my iPhone 4 in battery behavior. I still charge it every night and most of the time when I’m at my desk in my office.

From a hardware perspective, the iPhone 4S pretty much delivers as expected. The dual-core A5 processor zips along with plenty of headroom, smoothing out many of the rough spots in everyday usage that have started to creep in since the iOS 4.3 update. The camera upgrade boosts both still image and video (1080p) performance into the realm of most modern point-and-shoot cameras, although the lack of any optical zoom is still a big limitation. On the other hand, the wide availability of camera and photo enhancement apps pretty much make up for the lack of optical zoom. Battery capacity has increased minimally, but not enough to make any practical difference.

From the power efficiency standpoint, by far the most interesting new hardware feature is the new dual-antenna design, which eliminates the infamous “death grip” effect of the iPhone 4 and improves cellular reception in general. Combined with the new communications chip that boosts data rates (for GSM networks), the new radio setup is worth looking at—especially since we’ve seen that the radio can contribute even more to the energy equation than the display.

The runaway star on the software side with the iPhone 4S and iOS 5.0 is Siri. Reminiscent of a cross between HaL and the famous Star Trek “Computer,” Siri listens, seems to think, and generally does a better-than-expected job of carrying out your wishes. While still clearly early in the development cycle, Siri feels to me like the beginning of a paradigm shift where we may actually become just a productive without a keyboard as with one. I’ve dictated quite a few e-mail and text messages with Siri (sometimes while driving!), and accuracy is very good—or very bad. That to me is an indication of evolving and improving AI on the recognition side. And as is usual for Apple, the real genius of the Siri interface is the simplest part of it: You simply hold your phone up to your head to start talking to Siri. To everyone else, it just looks like you’re answering a phone call! I wish I thought of that…

Running the 4S though my usual battery (pun intended) of power tests running the Star Trek movie resulted in the following:

The results were surprising in several respects. First, the 4S seemed to be extremely efficient in the “Max Battery” mode. It played through the entire movie consuming just 0.6 Wh of energy. That would be more than 18 hours of continuous movie playing, although you can’t see much at the lowest brightness setting. This is almost a 40% improvement in energy efficiency vs. the iPhone 4! The new lower power A5 chip is likely at the heart of this result. These days video decoding is an almost-routine task, and can probably easily be handled on one of its cores.

Turning the display to full brightness (the “Max Brightness” test) shows the expected result. The energy cost of running the display at full brightness is about 0.6 Wh for the two-hour movie. The display on the 4S isn’t notably different than on the iPhone 4, so this is expected.

Turning up the sound to maximum (“Max Movie” mode) shows one other interesting change. On the iPhone 4, there was virtually no change in energy consumption between the runs with the sound muted or with the sound at maximum. On the iPhone 4S there is definitely a measureable difference, both in energy consumption as well as in the perceived loudness of the sound. In fact, with the sound at maximum, the tiny speakers in the 4S produced enough sound to make it annoyingly loud as I was trying to do some other work. I had to resort to my “manual” muting method (putting a piece of tape over the speaker) to conduct my tests.

Well, I’m about out of space and time for this post. Next time I’ll describe the results of testing the new iPhone 4S dual-antenna and modem chip setup. These results are very interesting.

In late breaking news, Apple just announced a software update, iOS 5.0.1, which among other things “fixes bugs affecting battery life.” No big surprise, as the complexity of today’s smartphones rivals any other computing platform—and dwarfs the others when it comes to power management. In particular, the interaction between hardware and software to minimize energy consumption is very difficult to model and predict, but the ramifications on battery life are immediate and sometimes ugly.

And by the way, if you are interested in learning more about low power hardware design, my colleague Josefina Hobbs is hosting a new series of short videos covering everything from introductory concepts to selected advanced low power design topics. Check them out here.

–Cary Chin is director of technical marketing for low-power solutions at Synopsys.

By Cary Chin
The iPhone 4S was announced today and frankly I was a little disappointed. No new iPhone 5, no 4G support, no bigger display or smaller form factor. But now that the initial disappointment has worn off, let’s take a look at what we DID get—pretty much the rumored iPhone 5 in an iPhone 4 package. There’s a faster processor with the A5, higher-resolution eight-megapixel camera for reasonable stills and 1080p video, a “fat” 64 GB version, wireless mirroring to HDTV displays via Apple TV, a world phone (GSM and CDMA support), and a whole host of new software features including expanded voice control, many new iOS 5 features, and iCloud to support wireless synchronization and cloud storage.

While I don’t have one to play around with yet, my first interest from a power standpoint will be to evaluate the impact of the A5 processor. We saw a measurable improvement in energy efficiency in the iPad 2 vs. the original iPad, partly attributable to the A5. Roughly doubling overall performance compared to the A4, the A5 is a dual-core processor and adds significant additional power-saving features to do more with less.

Even more interesting, though, will be an evaluation of a less-talked-about new hardware feature: A revamped antenna setup for the iPhone 5 is said to significantly improve reception and data speeds. That should mean fewer dropped calls. We’ll see about that because it won’t be hard to verify this claim. And if data reception is improved by any noticeable amount, I’m certain we’ll be able to see it in our standard “Star Trek streaming test.” With the Retina display remaining constant, we should be able to get some good comparison points on the new hardware.

And here’s the big secret in Apple’s strategy with the iPhone 4S—I expect that Apple TV unit sales will go through the roof. Wireless streaming to today’s huge HDTV displays for $99 is only a little more than double the cost of Apple’s $39 HDMI adapter (Apple Digital AV Adapter), which doesn’t even include the cable! Sign me up.

So no new iPhone 5, but plenty of new features to fiddle around with until the “5” arrives. See you in line!

–Cary Chin is director of technical marketing for low-power solutions at Synopsys.

By Cary Chin
We’ve been examining power efficiency of iOS devices for a while now, and it’s hard not to notice the relative trajectories of mobile operating systems and more traditional PC operating systems. With the recent release of OS X Lion, Apple is moving in the direction of converging capabilities of these platforms, with the clear goal of a more unified environment coming down the line.

When I first played with the iPad and iPad2, I thought I had purchased my last laptop computer. The portability and battery life of these tablets were so compelling that surely the days of the laptop were over, and it was only a matter of time before tablets ruled the portable computing category. And sure enough, in the last couple of years, tablets have multiplied faster than rabbits. But interestingly, none have taken significant share away from the runaway success of the iPad.

Then in late 2010 came the refresh of the MacBook Air, transforming an over-priced, under-powered specialty gadget into a mainstream computing device that has breathed new life into the entire laptop category. Sure, it was still at least one generation behind in raw compute power, but as we all know by now, it’s the combination of compute power with all of the other system parameters that determines utility today, and the 2010 MBA hit the center of the target. And to top it all off, less than one year later, the July 2011 MacBook Air refresh brings latest technology to this form factor, completing the repositioning of the MBA from a “snob’s machine” to one that can satisfy 80% of the market. I got my 13” MBA a few weeks ago, and have been impressed not only with its speed (1.7GHz Core i7 with 3MB cache, 4GB memory, and 128GB flash disk), but also its power efficiency (about five to six hours of typical use.) On the “Star Trek” power efficiency test, the 13” MBA fared very well—It made it through the entire 2:06 movie at maximum brightness and consumed about 22.5 Wh of energy, nearly the same as my 2010 11” MBA at 21.35 Wh.

My biggest dilemma now is which device(s) to bring with me? My arsenal now includes the iPhone 4, iPad 2, 11” 2010 MacBook Air, and 13” 2011 MacBook Air. All are very compelling, but a few factors make the determination easy, at least for now. First, the iPhone 4 is in. It’s the one device that I ALWAYS carry with me. Small, light, and utilitarian, it’s the 21st century Swiss army knife. The dilemma is, which additional device makes the cut? I’ve already decided that Internet access is best achieved through my phone via the personal hotspot feature, so that’s a wash. The iPad 2 is a wonderful machine. It still tops the list for the most compelling portable movie-watching device. Compared with all of the other devices, the display is big, crisp and clear, with deep rich colors, and exhibits the fewest artifacts. It’s a winner, but unfortunately iOS apps still restrict serious usage for entering or editing the standard documents that we all need to access, namely those created in Microsoft Office. Sure, it’s possible to upload/convert to Google Docs and edit online, but access isn’t 100%, and the interface is still a kludge in iOS, at best. I’m convinced that storage and editing in the cloud is the way of the future, but unfortunately, we’re stuck here in the present for now.

Which leaves me with two great choices for larger-format portable computing, the 2010 11” Air, or the new 2011 13” Air. The 2011 13” Air is a fantastic machine—blazingly fast and extremely power efficient. The display is significantly bigger than the 11” version, but so is its form factor. I’ve decided that my ultimate road warrior combo is my iPhone 4 coupled with the 11” MacBook Air. Everything I need, and super portable!

From the software standpoint, being able to run standard apps is certainly a compelling feature. Note to Microsoft: Where is that iOS Office app? Or maybe the operating systems are converging even faster. I’ve tapped the screen of my Air many times in the last few months, expecting a document to open, or a Web link to be followed. Certainly there are prototypes of touchscreen laptops deep in the research facilities at Apple. Plus, the large track pad and additional interface features in Lion (MacOS 10.7) are starting to make this laptop feel a lot like a tablet!

With this many great choices out there today, I can tell that my ultimate combo probably won’t last long. A converged iMacOS or big jump in performance and apps might well nudge the iPad (3?) back into the lead. But one thing’s for sure: I haven’t purchased my last laptop!

–Cary Chin is director of technical marketing for low-power solutions at Synopsys.

By Cary Chin
With the current popularity of all things extreme, from extreme dieting, extreme couponing and extreme hoarding, all the way to extreme sports and even extreme programming, I thought, “Why not Extreme Power Efficiency?” After all, power efficiency has been improving at a blistering pace for the last few years. Where will the hotspots and power bottlenecks be looking into the future?

Well, let’s start by rounding up the usual suspects. Dynamic and static power are the buckets into which we partition the energy that is used for computing (flipping bits), vs. the energy used to maintain power to the circuitry (sometimes also called standby power). For dynamic power, much of the focus today is on the back-end of the implementation flow—making sure that capacitances are minimized, dealing with many voltage areas or “islands,” and allowing dynamic variation of voltages and clock frequencies to conserve power. These problems aren’t completely solved today, and continue to expand as power architecture complexity increases, but they are reasonably well understood, with lots of people working on improvements in tools and methodologies. “Extreme” dynamic power efficiency might instead be measured in units of “transitions per function” to gauge the transition-efficiency of any implementation, combined with “joules per transition” for the physical layout and technology efficiency, to arrive at energy consumption estimates. As with any process, you can’t improve what you can’t measure, so thinking about measurements and metrics isn’t a bad place to start.

For static power, we are now pretty good at power gating or “shutdown” to minimize leakage power in unused blocks, and new technology improvements have at least postponed the dreaded explosion in leakage at smaller geometries. However, these problems won’t go away, so as we move forward, “extreme” thinking dictates that power gating will continue to become finer-grained—and to a certain extent the current move toward “3D” transistors is a move in this direction—with much better on-off characteristics such as faster performance and lower leakage. So as the technology enables new transistor designs that approach the “perfect switch,” the tradeoff between finer-grained power-gating vs. more efficient technologies continues to shift.

Finally, while it seems there’s an endless list of things that we need to (and can) worry about, remember that part of what we do everyday is to make practical decisions about priorities. Power efficiency is no different. Worrying about power consumption for one transistor may not seem like much, but multiply it by 3 billion transistors on a chip and suddenly you’re talking real power. At a macro level, an average no-load power (that means no phone on the other end) of 0.1W (0.5W just 3 years ago!) for a cell phone charger isn’t much, but multiplied by the 5 billion mobile phones in the world and 24/7, and you can see we’ve got a big problem. Extreme thinking doesn’t always point us to practical problems that need addressing immediately, but it does allow us to step “outside the box” for a bit just to see what might be out there.

–Cary Chin is director of technical marketing for low-power solutions at Synopsys.