Despite the recent doldrums in smartphone shipments, the stakes couldn’t be higher as several semiconductor vendors and OEMs announce a slate of new mobile system-on-chips (SoCs). The latest announcement is MediaTek’s latest flagship smartphone SoC: the Dimensity 9300. With the third generation of its Dimensity product family, MediaTek is boldly betting that higher performance will also provide greater power efficiency.

Smartphone SoCs have evolved from rather simple chips to the most complex integrated circuits (ICs) in the chip industry by combining several different (heterogeneous) processing elements along with graphics and baseband modem technology.

To reduce overall power use, mobile SoCs leverage a multi-tier central processing unit (CPU) architecture based on various Arm cores that trade off performance and power use. Dubbed the “big.LITTLE” architecture by Arm, SoC vendors combine Arm Cortex-A7x series CPU cores with Cortex-A3x or Cortex-A5x series CPU cores.

The theory behind this is that background and other lower-performance tasks can be allocated to run on the lower-power “LITTLE” CPU cores (A3x and A5x), while the “big” CPU cores (A7x) are powered on only for applications requiring higher performance. In 2020, Arm modified this architecture by adding an even higher-performance CPU series dubbed the Cortex-Xx, essentially creating a “bigger.big.little” architecture.

The use of these different power/performance CPUs has been the predominant method of architecting mobile SoCs for longer than a decade. Even Intel has recently adopted a similar methodology for its x86-based mobile PC SoCs.

However, sometimes bigger is better. Every SoC available, from smartphones to servers, is designed to execute the allocated tasks and shut down as quickly as possible to reduce power use. Theoretically, the power used by a larger CPU core may still be lower than a smaller, more power-efficient CPU core if the tasks can be executed more quickly to allow the processor to spend more time in a sleep state. (The power savings depend on the tasks: Some may be tied to real-time processing that is ongoing.)

With the Dimensity 9300, MediaTek is putting this theory to the test by configuring the processor with four of the latest Arm Cortex-X4 cores and four of the Arm Cortex-A720 cores in a “bigger.big” configuration.

Dimensity 9300 summary.

By comparison, the previous-generation Dimensity 9200 had a more traditional “bigger.big.little” configuration, with one Cortex-X3 core, three Cortex-A715 cores and four Cortex-A510 cores. In the Dimensity 9300, one of the Cortex-X4 cores will be optimized for performance with a peak frequency of 3.25 GHz, the other three Cortex-X4 cores can be clocked up to 2.85 MHz and the Cortex-A720 cores can be clocked up to 2.0 GHz. MediaTek believes that increasing demands on the mobile CPUs make the Cortex-A720 cores the most efficient option. The company also believes that this “bigger.big,” or “all big,” CPU configuration will give the Dimensity 9300 a performance boost over the competition.

To help Dimensity 9300 execute its tasks more quickly, the SoC also includes 8 MB of L3 cache and 10 MB of shared system cache, up 29% in total cache from the company’s previous generation; support for LPDDR5T memory at 9,600 Mbps, representing a 12% increase in memory speed; the latest Arm Immortalis-G720 graphics processing unit (GPU), delivering a 46% increase in peak performance and ray tracing; and the second-generation Semantic Analysis AI-ISP (image signal processor), capable of supporting Ultra HDR with up to 16 object segmentations/layers that can be independently enhanced and 4K video resolution at 60 fps.

Block diagram.

The Dimensity 9300 also features a next-generation neural processing unit (NPU) that the company refers to as the 790 AI processing unit (APU). The 790 APU provides a 2× increase in integer and floating-point operations while reducing power use by 45%. The APU 790 includes support for transformer models, mixed-precision INT4 quantization technology and MediaTek’s NeuroPilot memory hardware compression. According to the company, the new 790 APU is 8× faster than the previous generation and is capable of image generation in under one second using stable diffusion.

Advanced hardware compression technology.

MediaTek said these enhancements should allow the Dimensity 9300 to provide a 40% increase in peak performance with a 15% increase in performance at the same power or 33% lower power at the same performance as the previous generation.

n terms of AI performance, MediaTek is predicting the ability to handle up to 13 billion parameter models. Most of the mobile vendors appear to be targeting 7 billion to 10 billion parameters, considered the sweet spot for on-device AI applications, over the next year or two.

The Dimensity 9300 also adds dual independent secure processors, a first for MediaTek, to support both secure boot and secure computing to ensure a higher level of data security and privacy, which is a must with the growing number of security threats to mobile platforms.

For cellular connectivity, the Dimensity 9300 supports 5G Release 16 with four-channel carrier aggregation and up to 7-Gbps downloads in the sub-6-GHz frequency band, plus a built-in AI function to improve connectivity. The Dimensity 9300 also supports Wi-Fi 7 connectivity for up to 6.5-Gbps bandwidth with Xtra Range 2.0 technology to support greater Wi-Fi coverage.

The “bigger” and “big” CPU cores combined with all this other functionality increase die area, which raises costs. While the Dimensity series targets flagship smartphones, most of the OEMs that are likely to adopt the product are in China and other regions that are price-sensitive. Some of the die area costs are offset by the use of the third-generation TSMC 4-nm+ semiconductor manufacturing process. However, it is not clear what the total impact will be on the product profit margin at this time.

In total, the Dimensity 9300 looks like a beast of a mobile SoC. It will be interesting to see if MediaTek’s bet on “bigger.big” performance pays off in terms of performance efficiency and design wins. Tirias Research anticipates the introduction of products using the Dimensity 9300 in Asia, Europe and other markets throughout next year. Unfortunately, those of us in the U.S. may still be left out unless U.S. carriers choose to expand their smartphone options.

By: DocMemory
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