Trends in Processor Architecture of Mobile Phones: a Survey

International Journal of Advanced Science and Technology Vol. 29, No. 5, (2020), pp. 6265 – 6274

Trends in Processor Architecture of Mobile Phones: A Survey

Advaitha B1*,Mopuru Lahari1,Gopalakrishnan T2

UG Student1, Assistant Professor2 School of Computer Science and Engineering Vellore Institute of Technology, Vellore, India [email protected],[email protected] , [email protected]

Abstract Mobile’s has become a part and parcel of our lives. The brain of a mobile is its processor. The semiconductor device, CPU chip is placed inside chip package which reduces the heating effect. It is designed to operate at lower voltage compared to desktop and with an increased “sleep mode” capability. We can control the power levels of the mobile processor and can even turn of sections of chips when they are not in use. The so-called clock frequency is bought down in mobiles to increase the battery life. The year 2016 to 2020 focused more on improving the existing features than introducing new features. Mobiles had transformed from a device that was just used to communicate to a source of knowledge. This transformation is possible only with the help of improvement of processors. The aim of this paper is to study about the changes brought in the past 5 years in processors.

Keywords: Smart Phones, ARM Processor, Processor core

1. Introduction

Smartphone hardware principally consists of display (LCDs and LEDs), battery, system on a chip, memory and storage, modems, camera and sensors. The processors used in mobiles must be designed in a way that it emphasizes price, time to market, low power. Due to the presence of constrained resources of cost and power, and all real time computation requirements, the processors are designed to support a number of distinct characteristics such as limited programmability. The processors architecture must support all the complex user interface, dynamic operating environment and provide additional services. Multiple DSP’s or hardware coprocessors built by advanced architecture is required to fulfill all these additional services.

2. Mobile Processor Chipsets Types

2.1 Digital Signal Processor It is a specialized microprocessor that is designed to fulfill the needs of digital signal processing. Its goal is to filter or compress continuous analog signals. Early DSPs were implemented using bit slice chips. During the late 1970’s the first single chip DSPs were introduced. The cellular handsets can be implemented using 2 different approaches. The first method uses ASIC (Application Specific Integrated Circuit) techniques and the second approach emphasizes programmable DSPs. The embedded DSPs are widely adopted for VLSI styles

ISSN: 2005-4238 IJAST 6265 Copyright ⓒ 2020 SERSC International Journal of Advanced Science and Technology Vol. 29, No. 5, (2020), pp. 6265 – 6274 whereas the wireless phone market place is ruled by programmable DSPs for cellular telecom [1]. Analog transmission was used by the earlier mobile that is the 1G system that required a lot of power for transmission and had a major disadvantage of providing access to restricted users. Global System for Mobile Communication (GSM) evolved after the first generation of analog cellular signals used in first generation mobiles. The type one DSP processor served as an important embedded processor was used widely in second generation mobiles. Due to shorter product life cycle, the DSP architectures are much popular than the ASIC and hence are widely employed in GSM mobiles. Cheap and versatile design is enabled by the programmable DSPs for the cellular telephones. The first DSP was introduced by AT& in the year 1979 which was later improvised by the Texas Instruments. The storage and signal pathway for instructions and data was physically separated by the traditional DSP that used Harvard architecture. This was contrasted by the von Neumann architecture that used the same memory for storing both data and instruction. The instructions are executed using data memory and instruction memory. Simultaneous transmission is possible through separate data and instruction buses. Ultimately, the multiplication unit output is connected to an adder and hence, adding and saving all the partial results for further processing. The high memory bandwidth and multiple operand operations of the architecture enable the execution of function in fewer cycles.

2.2 System On Chip (SOC) System on chip is a single chip that integrates all the components of a computer or other electronic system into a single unit. The typical coin sized chip compresses central processor, graphics card, memory controller and other elements into a single unit. The power operation in the mobile is lowered by lowering the voltage of chip. Higher performance and low power designs had become reality with the introduction of highly integrated Soc’s that utilizes multicore technology to its maximum. Cache memory kind of improvement must be implemented in VLIW architecture for better performance. Instruction set customization is used to speed up the operation of mobile devices. Inorder to support more read and write operations, most instructions are present in 16 bit. We can effectively improve the memory utilization with the help of instruction set customization. For example, if we customize a 64-bit data types to 8-bit types there is an improvement in the overall performance. This is due to better operations per cycle in 8-bit than in 64-bit [2]. There is a recent talk that states that with the introduction of Network on Chip (NoC), the SoC would go outdated. The effectiveness of microprocessor can be increased by using SoC. The MediaTek launched HelioP70 with artificial intelligence which combines CPU and GPU that can effectively be use for advanced AI processing. With the introduction of new and powerful SoC, the flexibility reduces which makes the processor companies to build specially designed SoC for every device. However, with the invention of new materials and technologies we can overcome this disadvantage.

2.3 ARM Processors For Mobiles The modern-day smart phone uses ARM based processor. It is primarily based on RISC architecture which uses a 32-bit instruction set. Considering the fact that they show great performance in spite of using low power, its widely used in smart phones. Apple, Qualcomm etc design their own products based on the architecture provided to them by the ARM holdings which includes chip design and instruction set. The architectures that are used in low end and mid range smart phones range from ARMv5 to ARMv7a, whereas the high-end devices use ARMv8a. ARMv8a architecture has two execution state that is AArch32 and AArch64. The execution state AArch32 provides compatibility with ARMv7a architecture.

3. Comparative Study of the Processors in Mobile Phones

According to the recent study, the best mobile processor is Apple A13 Bionic which powers the iPhone 11 Lineup. Of all the processors used by the Android devices, the Snapdragon 865 is now the best processor which is followed by Exynos 990, MediaTek Dimensity 1000, Snapdragon 855+, and Kirin 990. The Apple A12 Bionic is the 5th best SOC and its slightly better than Snapdragon 855+ [3].

3.1 APPLE A13 Bionic Processor The Apple A13 Bionic processor is the new system-on-chip processor which powers the latest 11 series of Apple iPhone. Allowing some of the powerful features like 4K video at 60fps and slow-motion pictures well known as slofies, as well as spatial audio, the Apple A13 Bionic processor has been described as the Apple A13 Bionic as the fastest CPU and GPU ever in a smartphone. In short it can be said that this is an improvised version of the previous processor, the A12 Bionic, introduced by enhancing overall performance ,also offering gains in the power efficiency, and hence the battery life of the mobile [4]. It features an Apple-designed 64-bit six-core CPU, with two high-performance cores running and four energy-efficient cores. It comprises of– a six-core CPU, four core GPU, and an eight-core Neural Engine processor.

Figure 1:Apple A13 Bionic Processor [11] Four of the six cores on the CPU are low-powered cores which are dedicated to handling basic phone operations such as answering calls, launching Safari, delivering messages – while two bigger performance cores lie in active until you put more intensive processes into actionas in recording video or playing video games etc.

3.2. SNAPDRAGON 865 Snapdragon 865 is built on TSMC-improved 7nm “N7P” node which is almost the same process used by Apple’s A13 Bionic chip and manufactured using TSMC’s first-generation 7nm “N7” mode. Snapdragon 865 features an octa-core CPU with single primary ARM Cortex A77 core based on Kryo 585 assigned to run at high-performance. The balance cores comprise of three ARM Cortex A77 cores based on Kryo 585 running for mid-performance and four Cortex A55 cores based on Kryo 385 for usage of low power [5].

Figure 2: Qualcomm snapdragon processor[12] For the tasks related to the graphics intensity in Snapdragon 865, we have the latest Adreno 650 that offer a way better and faster graphics rendering over the Adreno 640 in previous Snapdragon 855. The latest Snapdragon 865 SoC with Adreno 650 is capable of featuring QHD+ 144Hz display (or UHD 60Hz). The Spectra 480 ISP on Snapdragon 865 has made quite improvisation to the camera performance which can process images up to 200MP [6].

3.3. EXYNOS 990 Exynos 990 is a 64-bit octa-core ARM high performance mobile system on a chip designed by Samsung and introduced in the year 2020. The processor is manufactured or fabricated to be more precise on Samsung's 7nm EUV FinFET process and features 8 cores in a tri-cluster configuration which had two five big cores, two Cortex-A76 middle cores, and four Cortex-A55 little cores. The Exynos 990 processor features the 5th generation custom CPU for computing the power required for complex usage cases in the 5G era. The tri-cluster CPU of exynos 990 which is a distinctuve attribute of it delivers up to 20% enhanced performance than its predecessor.This Combined effect of the Cortex-A76 dual- core and the Cortex-A55 quad-core, the Exynos 990 processor gives us the optimal performance and better power efficiency for seamless mobile experiences.[10]

Figure 3: Samsung Exynos 990 processor [13]

Furthermore, it holds LPDDR5 memory’s data rates of up to 5,500 megabits per second for wider memory bandwidth than its predecessor. This allows a smartphone to efficiently transfer or deliver huge amount of info needed for 5G communication, AI applications, graphically demanding games, ultra-high resolutions videos, and many more.

3.4 Mediatek Dimensity 1000 The MediaTek Dimensity 1000 comprises of an octa-core (4+4) CPU. It consists of four ARM Cortex-A77 “big” cores with four ARM Cortex-A55 “little” cores. The core configuration of the SoC is interesting as it’s a 4+4 configuration whereas Samsung and Huawei’s HiSilicon both consist of 2+2+4 configuration in their the Exynos 990 and the Kirin 990 MediaTek is the first to use ARM’s Mali-G77 GPU, which has also made its way to the upcoming Exynos 990. The company is also promoting its 3rd generation artificial intelligence Processing Unit for various operations, which has more than double the performance of MediaTek’s previous APU. The Dimensity 1000 comprises the world’s first five-core image signal processor combined with MediaTek’s Imaging and technology. It supports 80MP camera sensors at 24fps along with a range of multi-camera options such as 32MP + 16MP dual cameras [7]. The Dimensity 1000 has an integrated 5G modem, which gives it an upper hand over the Snapdragon 855 and the Exynos 990. This brings it in level with the Kirin 990 5G.

3.5 KIRIN990 Kirin 990 5G is a 64-bit high-performance mobile ARM 5G SoC designed by HiSilicon which made its debut through the Huawei Mate 30 Pro. Made on TSMC's enhanced 7nm+ EUV process, the 990 5G incorporates two high frequency Cortex-A76 cores along with two medium frequency Cortex-A76 cores along with four Cortex-A55 cores .

Figure 4: Huawei Kirin 990 5G[14] The Kirin 990 possesses an improvised version of the Kirin 980’s AI-based scheduler. The Kirin 990 hold up to 64-megapixel cameras. Kirin 990 devices are more powerful and in real-world usage, it would be nearly not at all possible to differentiate when compared to other flagship SOCs[8]. TABLE OF COMPARISION Apple A Mediatek Snapdragon 13 Exynos 990 Dimensity Kirin 990 865 Bionic 1000

Number 6 8 8 8 8 of cores

Clock 2.65 1.8 GHZ 7.35GHZ 4.6GHZ 2.86,2.36,1.85GHZ Speed GHZ

Supports Supports 80 4K video graphically Mp camera at 60 fps, QHD+144Hz demanding sensors at slopies display. It can games and 24fps along Can hold upto 64 Display and process image provides with 32 mega pixel camera. special upto 200 Mp ultra high Mp+16 Mp audio. resolution dual video. cameras.

4. Mobile Graphic Processors

A mobile graphic processor is useful for performing parallel operations such as it is used for 2D data as well as for zooming and panning the screen. A GPU is very important for smooth decoding and rendering of 3D animations and video. The more the GPU is developed to a higher complexity, the higher the quality and the faster and smoother the motion in games and films. Among thousands of graphic cards in the market, the ones which proven themselves to be the best of all among various aspects are AMD Radeon RX 5700, Nvidia GeForce, RTX 2080 Ti followed by AMD Radeon RX 5600 XT and Nvidia GeForce RTX 2070 Super.

4.1 AMD RADEON RX 5700 The Radeon RX 5700 is a performance-segment graphics card manufactured by AMD and launched in the year 2019. It possesses 2304 shading units, 144 texture mapping units and 64 ROPs. This GPU operates at a frequency of 1465 MHz, which can be boosted up to 1725 MHz, memory is running at 1750 MHz. Straight away to elaborate, this built-for-gaming graphics architecture increases performance-per-clock by 1.25x, automatically drawing more performance out of the graphics card. And, when the higher core counts of these GPUs are taken into consideration, it’s no wonder that the AMD Radeon RX 5700 outshines of everything.[15]

Figure 5: AMD Radeon 5700 XT[16]

The AMD Radeon™ RX 5700 Series GPUs are given with the all new RDNA architecture and are designed from the ground up for exceptional quality performance of 1440p, exceptional power-efficiency for high-fidelity gaming. It's also equipped with the latest 8GB of GDDR6 high-speed memory and PCI Express 4.0 support, giving out twice the bandwidth.

4.2 The NVIDIA GEFORCE RTX 2080 Ti The Nvidia GeForce RTX 2080 Ti offers a look into the best world of graphics technology, and to want the, we must have to have to pay the steep price. Once, we get in, we would be going to need the best processor and gaming monitor to really take the Nvidia GeForce RTX 2080 Ti to its perks. This GPU also possesses two additional types of cores its predecessors as in The Nvidia get force RTX 2070 Ti was never featured in, that ate in the form of RT and Tensor cores.[18] The RTX 2080’s Ti’s 68 RT Cores power ray tracing allows this graphics card to control much more complex, real-time lighting scenarios and natural shadows than the 1080 Ti ever could.

Figure 6:Nvidia GeForce RTX 2080 Ti[19] It comprises of 4352 shading units, 272 texture mapping units and 88 ROPs. Also featured with 544 tensor cores which help in improving the speed of machine learning applications. The card also has 68 raytracing acceleration cores which is another important benefactor.

4.3 ZOTAC GEFORCE GTX 1080 Not only is the Zotac GeForce GTX 10bo Ti Mini a full-blown GTX 1080 Ti without making it ineffective in any way, the card even has a slightly higher boost clock compared to the Founder’s Edition. It’s still the base model of the Zotac card however, placed just above the Founder’s Edition in the products.

Figure 7: Zotac GeForce GTX 1080[20] Despite its waiflike nature it's still a full-blown GTX 1080 Ti and has specs that are similar to other "partner" versions of the 1080 Ti, though it has less audacious features and the cooling effect. Instead of a huge tri-fan setup like in the company's founder edition, at an Extreme, it uses just two fans; one 90mm and the other 100mm. [21] TABLE OF COMPARISION AMD Radon RX Nvidia GeForce Zotac GeForce 5700 RTX 2080 Ti GTX 1080 Operating 1465 MHZ which can 1350 MHZ which can 1392 MHZ which can frequency be boosted upto 1725 be boosted upto 1545 be boosted upto 1506 MHZ, memory MHZ, memory MHZ. running at 1750 MHZ. running at 1750 MHZ. Texture Mapping 144 272 48 Shading units 2304 4352 768 ROP 64 88 32 Architecture RDNA NVIDIA Tuning Pascal

5. Conclusion

The high competition among the companies has led to the development of power efficient mobile processor and this competition makes sure the processor is improvised every day. All the modern mobile processors are ARM based, designated with fancy names by different cellular companies. The introduction of advanced mobile CPU’s , the smartphones in the market becomes more powerful with new GPU cores, memory interfaces and other advanced features. The device performance is improved through the exploration of next generation processor architecture via SOC. There has been a tremendous increase of mobile processor unit in the market that led to the development of powerful cell phone devices. With the development of Artificial Intelligence, the processor architecture must be designed to support the new features without compromising other factors such as low power consumption, user interface performance, time to market etc.

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[19] https://in.pcmag.com/nvidia-geforce-rtx-2080-ti-founders- edition/125650/nvidia-geforce-rtx-2080-ti-founders-edition [20] https://www.paisawapas.com/p-zotac-geforce-gtx-1080-founders-edition- graphics-card-zt-p10800a-10p- 8gb-gddr5x-8934743 [21] https://www.zotac.com/product/graphics_card/zotac-geforce-gtx-1080-ti- arcticstorm-mini