Thursday, August 28, 2014

MediaTek well positioned for smartphones, widely adopts Cortex-A53 for upcoming platforms

MediaTek has announced several new smartphone chips this year, most of them exclusively using ARM's efficient new 64-bit Cortex-A53 core in various configurations. This includes major platforms targeting the entry-level and mainstream segments scheduled to be shipping this year, and a new high-end platform scheduled to be shipping near the end of the year. These are also the first MediaTek SoCs to integrate a 4G LTE baseband.

Existing low-end 3G platforms

MediaTek currently dominates the worldwide cost-sensitive smartphone market, shipping cost-effective, power-efficient SoCs that integrate 3G baseband and other functionality. These solutions will reach shipments of hundreds of millions this year.

The MT6572 is a dual-core Cortex-A7 SoC targeting ultra-low-cost smartphones that started shipping towards the end of 2013. The combination of Cortex-A7 CPU cores and 28nm process technology ensures acceptable performance and power efficiency. Cost is reduced by incorporating a relatively small 256 KB L2 cache, cost-effective Mali-400 MP1 GPU and integrating additional digital connectivity functionality relating to WiFi and other standards. The MT6572M is a lower-clocked version of the MT6572. In 2014, MediaTek released the MT6571, a cost-reduced platform based on the MT6572 targeting low-cost 2G/EDGE devices in emerging markets.

The MT6582 is a quad-core Cortex-A7 SoC targeting low-cost smartphones that started shipping towards the end of 2013. Manufactured at 28nm, it is power-efficient with good performance for its segment. Apart from the higher number of CPU cores, the MT6582 also has a larger L2 cache (512 KB) and more GPU cores (Mali-400 MP2) when compared to the MT6572. It also integrates connectivity functionality such as WiFi. The MT6582M is a popular lower-clocked but cheaper version of this chip.

First "true" octa-core CPU

The MT6592 is an octa-core Cortex-A7 SoC clocked at a fairly high frequency (1.7 GHz) targeting the higher segments, which is a significant departure from MediaTek's previous focus on lower segment devices. It started shipping in the beginning of 2014 and has seen widespread adoption among Chinese manufacturers. The power efficiency and small die size of the Cortex-A7 keeps cost and power consumption in check despite the presence of eight cores.

Compared to octa-core chips following ARM's big.LITTLE design that existed at the time, in which the number of active cores was limited to four, the MT6592 was the first chip allowing concurrent use of all eight cores. big.LITTLE-based chips at the time also had problematic power consumption (which to a large degree continues to be the case today) that limited their viability, especially for smartphones. Although the use of eight CPU cores was ridiculed by some competitors and observers at the time, subsequent developments in smartphone SoC CPU technology suggest that this chip was in fact revolutionary and a sign of things to come.

Like the low-end SoCs, the MT6592 uses a 32-bit DRAM interface, clocked up to 666 MHz, which limits memory bandwidth and is a bottleneck for performance given the otherwise higher performance characteristics of the chip, such as the octa-core CPU and Mali-450 MP4 GPU. It has been reported that, probably due to the impact of limited memory bandwidth, MT6592-based devices suffer from reduced performance and power-efficiency when used with a 1080p display because of the associated higher demands on the memory subsystem, meaning that a 720p or lower display results in much more balanced performance. The commonly used MT6592M is a lower-clocked version of the MT6592.

MediaTek currently shipping 4G using stand-alone baseband

MediaTek has been late with the introduction of basebands with 4G network support, and is still not shipping a SoC with integrated 4G baseband, a feat that competitor Qualcomm already achieved almost a year ago. However, it already supports 4G smartphones with an alternative solution, a separate baseband/modem chip.

MediaTek is currently shipping in 4G LTE-enabled platforms using its stand-alone MT6290 2G/3G/4G baseband with support for LTE R9. This chip is used in conjunction with MediaTek's existing cost-effective quad-core Cortex-A7 MT6582/MT6582M SoC platform and its mid-range octa-core Cortex-A7 MT6592/MT6592M platform. The use of two chips is inherently more costly than a SoC with an integrated 4G baseband, and essentially means the chipset contains duplicated 2G/3G baseband functionality, although the MT6582 is a chip with low manufacturing cost which means that MediaTek may still achieve acceptable margins even with the additional chip. Judging from early reviews, the use of two chips does not seem to have a significant impact on power efficiency.

Update (September 7, 2014): New models introduced by smartphone vendors at the IFA trade show widespread adoption of Snapdragon 400 and 410 SoCs with integrated 4G in lower-end models, including models from manufacturers targeting lower-end segments (such as Alcatel) where MediaTek previously supplied chips for the vast majority of models. This suggests that the two-chip solution with the MT6290 is not very appealing to the market for reasons such as cost, as well as being a bad match for the very tight capacity situation at TSMC.

Cortex-A53-based platforms targeting entry-level to mainstream

The MT6732, with a quad-core Cortex-A53 CPU at 1.5 GHz, is targeted at the higher regions of the entry-level segment with display sizes up to 720p. Manufactured using TSMC's 28nm HPM process, it includes a Mali-T760 MP2 GPU and integrates MediaTek's new 4G baseband supporting LTE R9 Cat 4. The SoC uses of a single-channel 32-bit LPDDR3 DRAM interface clocked up to 800 MHz, which similar to the DRAM configuration used in existing cost-sensitive platforms, although the maximum clock frequency has been increased. Volume availability is expected in Q4 2014.

The MT6752 is mid-range platform with a symmetric octa-core Cortex-A53 CPU at 1.7 GHz. MediaTek already has experience with a similar CPU configuration with its MT6592 with octa-core Cortex-A7. It is targeting the mainstream segment with a display size up to 1080p. Also manufactured using TSMC's 28nm HPM process, it includes a Mali-760 MP4 GPU, with twice the number of cores compared to the MT6732, and integrates MediaTek's new LTE R9 Cat 4 baseband. It has the same DRAM interface as the MT6753, keeping cost down, but limiting memory bandwidth which potentially impacts performance, especially for larger display sizes such as 1080p. Volume availability is expected for Q4 2014.

It is possible that the MT6732 and/or MT6752 already make use of the frame buffer compression or smart composition technologies offered by ARM, which are part of new platforms associated with recent CPU cores such as Cortex-A53, existing and upcoming Mali GPUs, and newly introduced ARM video (VPU) and 2D graphics (DPU) cores. These techniques can significantly reduce memory bandwidth requirements, which is important given the limitations on memory bandwidth in the MT6732 and especially the higher-performance MT6752.

Finally, the MT6735 is a derivative of the MT6732 that adds EVDO network technology, making it suitable for markets such as the US where some carriers continue to use network technology with an origin in CDMA. This is a market that Qualcomm has historically dominated. This development was reportedly made possible by MediaTek obtaining licenses from VIA Technologies. It is scheduled for shipment in 2015.

High-end Cortex-A53-based platform

The MT6795 is a high-end platform with a symmetric octa-core Cortex-A53 CPU up to 2.2 GHz, targeting the high-end segment with display size up to 2560x1600. Manufactured using the 28nm HPM process, it reportedly has a high-performance PowerVR G6200 GPU, and also integrates a 4G LTE baseband. A critical feature of this chip is the use of a dual-channel LPDDR3 DRAM interface, clocked up to 933 MHz. The dual-channel interface doubles memory bandwidth compared to other MediaTek platforms, greatly improving performance potential, in line with current high-end SoCs such as Qualcomm's Snapdragon 800/801/805 platforms. MediaTek has announced that devices with the MT6795 will be commercially available by the end of 2014.

It does not look like a coincidence that the model number of this chip is similar to the big.LITTLE-based MT6595 using Cortex-A17 and Cortex-A7 cores that was announced much earlier, which has a similar GPU and DRAM interface, strongly suggesting that the MT6595 will have relatively limited viability and that the MT6795 is in fact the smarter, cheaper and more power-efficient replacement for it. This provides strong evidence that MediaTek, despite earlier prominent announcements about its heterogeneous multi-processing architecture dating back to 2013, is currently de-emphasizing big.LITTLE architectures in favor of less complicated, much more power-efficient and more cost-effective multi-core configurations.

Update (January 9, 2015):

The MT6595 has been somewhat more succesful than estimated in this article, with at least two high volume smartphone models adopting it (Lenovo Vibe X2 and Meizu MX4), although it is not been very widely adopted. Meanwhile, not much further information has yet been heard about the MT6795, which could point to possible delays or reflects NDAs and a policy of secrecy regarding this product on the part of MediaTek. MediaTek continues to use big.LITTLE CPU designs for smart TV and some tablet products, but I believe for the mobile market (smartphones and tablets), Cortex-A53-based SoCs have a much greater potential for success.


MediaTek's early adoption of power-efficient, in-order pipeline Cortex-A7 cores means it has significant experience with the type of CPU architecture (four or eight extremely low-power, medium performance cores) that is becoming increasingly important even for high-end platforms. The expertise gained from the octa-core MT6592 is likely to serve MediaTek well for upcoming platforms. Even Qualcomm is quickly moving into this direction, but MediaTek is still likely to have some competitive advantage due to its previous experience. This will give MediaTek the opportunity to further extend its reach into higher-end segments.

At the same time, MediaTek has faced challenges. It is obvious that its prominent investment in big.LITTLE heterogeneous multi-processing architectures (such as the high-end MT6595 smartphone SoC and the MT8135 tablet SoC announced earlier) has brought a limited amount of benefit in the mobile space, with somewhat limited shipment potential due to cost, relatively high power consumption and other issues.

The late introduction of SoCs with an integrated 4G baseband has already affected MediaTek's market share in the upper part of the low-end segment, which is being encroached by Qualcomm's Snapdragon 400 platform, which has already offered an integrated 4G baseband for some time, and has been further updated with the Cortex-A53-based Snapdragon 410 platform.

MediaTek faces wafer capacity shortages at TSMC, where a large part of advanced chip manufacturing capacity has been taken up by Apple. Apple, as well as Qualcomm, are large TSMC clients with very deep pockets and can invest many billions of dollars in purchase commitments, and have done so, potentially shutting out MediaTek to a certain degree. The tight chip supply situation is likely to affect MediaTek's sales and flexibility of production.

The smartphone SoC market is also complicated by Qualcomm's large patent/IP position, based on which it strives to levy high royalties on smartphones, especially those using chips from competitors. This situation has resulted in Qualcomm obtaining an overwhelmingly large share of the high-end smartphone SoC/baseband market and the failure of many traditional competitors. However, recent developments in China have undermined Qualcomm's ability to enforce royalties and licensing fees, and Samsung also seems to be moving away from its uneasy strong dependence on Qualcomm. This may already have resulted in increased demand for MediaTek chips, although this demand may be higher than MediaTek's current ability to supply.

Sources: MediaTek websiteMediaTek (MT6795 press release), Wikipedia (MediaTek), ARM (Cortex-A53 page), ARM (ARM Frame Buffer Compression), ARM (Smart Composition)

Updated (January 9, 2015):  Update status MT6595 and other big.LITTLE designs from MediaTek, and status of MT6795.

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