Understanding Qualcomm's Snapdragon 810: Performance Preview
by Joshua Ho & Andrei Frumusanu on February 12, 2015 9:00 AM EST- Posted in
- SoCs
- Qualcomm
- Mobile
- Gobi
- Snapdragon 810
WTR3925
There are a few things that are important when talking about a transceiver. To recap, transceivers have a few key elements. On the receive side, we see the need for low noise amplifiers, down-converters, and narrow-band amplifiers. On the transmit side, we need a driver amplifier, up-converter, and another set of narrow-band amplifiers. While most of RF360 is built on relatively old process nodes for CMOS technology, the transceiver can be built on newer CMOS processes because it’s doesn’t have to handle the level of signal that the rest of the front end does.
At a high level, the WTR3925 really brings two new capabilities to the table. First, it does away with the need for a companion transceiver in order to achieve carrier aggregation, which the WTR1625L/WFR1620 combination provided. It seems that this is due to the need for additional ports on the transceiver, which the WTR1625L lacked. The other improvement is that WTR3925 moves to a new 28nm RF process, as opposed to the 65nm RF process used for the WTR1625L.
As a quick aside, RF processes are largely similar to CMOS processes, although with a few modifications. These changes can be thicker metal in interconnects between transistors and memcaps, which are analogous to capacitors in DRAM. Qualcomm claims that this will drive down power consumption, however this is a product of a new architecture that takes advantage of the smaller process node. Unlike digital logic such as what we see on the baseband, RF does not directly benefit from scaling to lower processes. In fact, there is a chance that scaling to lower process nodes can hurt power consumption because even though the transistor can operate faster, there is more noise As a result of this noise, the amplifiers in the transceivers may need more stages and more power in order to achieve the same noise figure.
MDM9x35
While baseband was previously one of the most popular topics in RF, as can be seen by this article RF is much more than just the baseband. However, the baseband is a critical part of the chain. The RF front end is critical for reception and a myriad of other issues, but feature support and control of the front-end lies with the baseband. The baseband must properly interpret the information that the front-end provides and also send out information to the front-end to transmit.
Fortunately, the baseband is implemented with digital logic, so there are significant benefits to moving to the latest and greatest CMOS process node. Lower voltage (and therefore power) is needed to drive the transistors, and it becomes easier to drive higher performance in the DSP. In the case of the MDM9x35, we see that there's a QDSP clocked at 800 MHz for modem functions, and a 1.2 GHz Cortex A7 for functions such as mobile hotspot.
In the case of MDM9x35, there are two major contributors to the reduction in power consumption. The first is the move from 28nm HPm to 20nm SoC. While 20nm SoC doesn’t utilize FinFET, we still see scaling in power, performance, and density. The other area where we see power savings is better implementation of various algorithms. As a result, we should see around 20-25% power savings with the same workload.
MDM9x45
In the time since the first MDM9x35 devices were launched, Qualcomm has also iterated on modems. With the 9x45 generation, we see a move to category 10 LTE, which includes 450 Mbps maximum download speed when aggregating three 20 MHz carriers, and two 20 MHz carriers on the uplink for a maximum of 100 Mbps. Although the Snapdragon 810 doesn't have a 9x45 IP block for the modem, the Snapdragon 810 does support up a maximum of 450 Mbps for download with category 9 LTE. However, there is no uplink carrier aggregation in such a scenario. Uplink carrier aggregation is only possible with category 7, which limits downlink speeds to 300 Mbps.
Qualcomm claims that the MDM9x45 should bring around 40% energy savings in an LTE carrier aggregation scenario when compared to the MDM9x25 modem. In addition, these new modems bring in a new generation of GNSS location, with support for EU's Galileo constellation. It's likely that the DSPs and other aspects of this modem have been beefed up relative to the 9x35 and 8994 modems to enable category 10 data rates.
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TerdFerguson - Thursday, February 12, 2015 - link
I'm inclined to agree with you, especially after seeing the dual-channel 32-bit bus being described as having a total of 64 bits. Wow, that's as bad as marketing for 1990s consoles.extide - Thursday, February 12, 2015 - link
How is that bad marketing? A dual channel 32-bit bus IS effectively 64-bits wide ...dawheat - Thursday, February 12, 2015 - link
The reference platform has a 6.2” display - making it quite the gigantic phone. I'm guessing it avoids thermal issues which may impact other, more normal size phones.Andrei Frumusanu - Thursday, February 12, 2015 - link
The preview tests were actually done on the MDP tablet, not the MDP phone.dawheat - Thursday, February 12, 2015 - link
Ouch - then this is really best-case performance of the S810 as I'd imagine the tablet MDP has way higher thermal headroom than the phones it's being compared to.lopri - Thursday, February 12, 2015 - link
I am usually very harsh on reviewers, but I do not think your argument holds up. Exynos 5433 is a vanity product. While technically interesting, it is used for one product (afaik) and even that product is not widely available. I would definitely prefer to learn the improvement of the S810 over S800/S805, being Qualcomm's generational product.And it is not like the review tried to hide the Exynos 5433 or anything. The numbers are right there for you to see. Furthermore, AT covered the Exynos 5433 very extensively only a few days ago.
Likewise, throttling or power is meaningless at this stage without knowing what the shipping product is going to be like. And I expect to see those information in due time. Unless you can point to false benchmark data, I do not see the merit in picking on every single aspect of an SOC that was not covered (yet).
Not everyone wants to read corporate conspiracy theories on a tech article, either. I, for one, do not like to read unverified rumors in a technical article.
Only thing that I agree with you about is the missing clock frequency information on the charts. But again, the focus is rightfully on S805 v. S810. I will give the authors a benefit of doubt.
Only thing that I do not like about the article is its timing. I mean, I haven't even finished the Exynos 5433 article yet and there are already 2 laptop articles and now an introduction to the S810.. It's too much information for me to digest. Obviously this is a subject point, and I do not expect everyone to agree with me.
warreo - Thursday, February 12, 2015 - link
Exynos 5433 is indeed a vanity product, nobody is arguing otherwise. You are missing the point that I made earlier. Exynos 5433 is the immediate predecessor to the 7420. Hence, comparing the S810 to the 5433 is a good starting point for how the S810 will compare to the 7420, and it would be one completely based on real, hard data, not just speculation. Are you honestly saying that you would not be interested in a better preview of how the S810 vs. Exynos 7420 will shake out?lopri - Thursday, February 12, 2015 - link
I mean, if AT really wanted to boost S810's image the authors could have omitted the number from 5433 in Geekbench sub-score comparison. The rest of the charts also look free of manipulation, so I do not see how you get the impression.As you can see from this very comment section, not everyone is impressed by the S810. Apparently the authors did not do a good enough job - you know, the job you are insinuating here.
warreo - Thursday, February 12, 2015 - link
True enough, but the fact that AT provides the 5433 data makes it more mystifying why they almost completely gloss over it in the text (not to mention not provide the % differences in the tables). Josh and Andrei have already stated they intentionally kept the focus on S805 vs. S810, but my point is this would be a much stronger article if there was more depth given to the Exynos 5433 comparison. Clearly, I'm not the only one who thinks so.Tchamber - Friday, February 13, 2015 - link
@warreoGet over yourself. So far the 5433 has made it into one product. We all know that it's a good performer, but the Snapdragon line makes it into many more devices...always has. What your asking would be like me writing to Car and Driver and saying "hey, you are guys are doing your comparisons wrong. I want you test your Corvettes, Camarros, and GT500s against a Lamborghini Aventador." Well, they have all the test results from the Lamobo...but that's just not what the others were made to compete with, so it would be meaningless to run them against each other at the road course. Do your own math if you don't like not seeing a percent sign with easy to digest material. All the time you've been talking down to AT you could have posted your own conclusions and helped out all those people who agree with you.