The Cortex-A76 is ARM’s latest high-performance CPU core designed for mobile computing. It offers substantial improvements in performance and power efficiency over previous ARM cores like the Cortex-A73 and Cortex-A75. The Cortex-A76 is found in some of the latest system-on-chips (SoCs) used in smartphones, tablets and other mobile devices from companies like HiSilicon, Samsung and Qualcomm.
Overview of Cortex-A76
The Cortex-A76 CPU was announced by ARM in May 2018 as the next generation successor to the Cortex-A75. It uses ARM’s new DynamIQ technology which allows for more flexible CPU configurations in multi-core SoC designs. The key highlights of the Cortex-A76 are:
- Up to 35% higher performance compared to Cortex-A75
- 40% better power efficiency over Cortex-A73
- Supports speeds up to 3GHz
- Compatible with DynamIQ clustering technology
- 7nm and 10nm fabrication process
- ARMv8.2 64-bit instruction set architecture
The Cortex-A76 microarchitecture has been optimized to deliver maximum performance gains while staying within a mobile SoC’s tight thermal constraints. It achieves this through improvements such as an enhanced 10-stage pipeline, increased dispatch and retirement bandwidth, larger out-of-order execution window, and improved branch prediction accuracy.
For power efficiency, the A76 implements extensive clock and power gating techniques. It can dynamically activate or deactivate specific logic blocks based on workload requirements. The A76 can also scale voltage and frequency independently, allowing power draw to be minimized while maintaining performance. Overall, ARM claims the A76 provides laptop-class processing power within a smartphone power budget.
Kirin 980 – First Mobile SoC with Cortex-A76
The HiSilicon Kirin 980 was the first SoC to use the Cortex-A76 CPU core. Announced in August 2018, the Kirin 980 powers Huawei’s Mate 20 series of flagship smartphones. Key details include:
- TSMC 7nm process technology
- Octa-core CPU with 2 x Cortex-A76 @ 2.6GHz + 2 x Cortex-A76 @ 1.92GHz + 4 x Cortex-A55 @ 1.8GHz
- Mali-G76 MP10 GPU
- Dual NPUs for on-device AI processing
- Support for LPDDR4X RAM and UFS 2.1 storage
The dual configuration of Cortex-A76 cores running at different max clocks allows the Kirin 980 to balance performance and power efficiency. The ‘big’ A76 cores are used for intensive workloads while the ‘medium’ cores handle routine usage. Compared to the Kirin 970 and its Cortex-A73 cores, HiSilicon claimed a 20% boost in CPU performance from the A76. The Kirin 980 also featured a new Mali GPU and dual NPU to deliver excellent gaming, camera and AI experiences.
Exynos 9820 – Samsung’s First Cortex-A76 SoC
The Exynos 9820 is Samsung’s latest flagship mobile SoC featuring four Cortex-A76 cores. Key specifications are:
- 8nm LPP process
- Octa-core CPU with 2 x Custom Mongoose M4 @ 2.73GHz + 2 x Cortex-A75 @ 2.31GHz + 4 x Cortex-A55 @ 1.95GHz
- Mali-G76 MP12 GPU
- LTE modem with 2Gbps download speeds
- Support for UFS 3.0 storage and LPDDR4X RAM
Instead of exclusively using Cortex-A76 like the Kirin 980, Samsung employed a tri-cluster CPU design on the Exynos 9820. The two ‘big’ cores are Samsung’s own custom Mongoose M4 cores that are even faster than Cortex-A76. For better power efficiency, they are coupled with two A75 medium cores and four A55 little cores. Even though it has a lower peak clock, the Exynos 9820 delivers similar overall performance as the Kirin 980 while consuming less power thanks to its 8nm process.
Snapdragon 855 – Qualcomm’s Flagship Cortex-A76 SoC
Key details of the Snapdragon 855 SoC include:
- TSMC 7nm process
- Octa-core Kryo 485 CPU with 1 x Cortex-A76 @ 2.84GHz + 3 x Cortex-A76 @ 2.42GHz + 4 x Cortex-A55 @ 1.8GHz
- Adreno 640 GPU
- X24 LTE modem with 2Gbps peak download
- Qualcomm Aqstic audio codec
- Snapdragon Elite Gaming features
Unlike HiSilicon and Samsung, Qualcomm uses a semi-custom ARM core design license for its flagship Kryo CPUs. The Kryo 485 CPU on Snapdragon 855 comprises of four Cortex-A76 derived cores along with four A55 cores. With a prime core clock of 2.84GHz, the SD855 delivers leading Android performance that can rival Apple’s latest A12 processor.
Coupled with the Adreno 640 GPU and gaming enhancements like anti-cheat extensions, the Snapdragon 855 brings desktop-like gaming experiences on mobile. It also features an advanced AI engine and modern connectivity options like 5G and WiFi 6. Leading Android phones like the Galaxy S10, OnePlus 7 and LG G8 all utilize the SD855 platform.
Performance and Power Benefits of Cortex-A76
Compared to previous designs like the A73 and A75, the Cortex-A76 brings substantial improvements in processing power and power efficiency. Here are some examples:
- 35% faster throughput than Cortex-A75 at the same clock speed
- Up to 40% better power efficiency versus the A73
- Over 2x peak multi-threaded performance versus A73
- Up to 30% reduced power consumption for similar performance levels
These gains come from the microarchitectural enhancements in the A76 like the deeper pipeline, improved branch prediction, larger buffers and windows, and advanced power management techniques. While absolute performance varies based on factors like process node, frequency and SoC implementation, the Cortex-A76 clearly delivers laptop-class processing capabilities within a smartphone form factor and power budget.
Successor Cortex-A77 Announced in 2019
In May 2019, ARM announced the next iteration in the series – the Cortex-A77 CPU. It builds upon the A76 design and associated DynamIQ technology. ARM is touting a 20% increase in performance over the A76 without any impact on power, latency or area. Key improvements include:
- Enhanced branch prediction and prefetch
- Better instruction cache and MMU prefetch
- Increased dispatch bandwidth
- Memory subsystem enhancements
Just like the A76, the Cortex-A77 is aimed at premium mobile computing segments. It will likely debut in 2020 inside new chips from HiSilicon, Samsung, Qualcomm and MediaTek. Phones powered by the A77 can be expected to set new performance benchmarks while retaining all-day battery life.
Conclusion
The Cortex-A76 represents a major performance leap for ARM in the mobile space, bringing laptop-class processing capabilities to smartphones and tablets. Leading Android SoCs like the Kirin 980, Exynos 9820 and Snapdragon 855 have already adopted the Cortex-A76 cores. Compared to earlier designs like the A73, the A76 delivers substantially better throughput and power efficiency.
With the just-announced Cortex-A77, ARM aims to extend these performance gains even further. Mobile SoCs utilizing DynamIQ and newer CPU cores like the A76, A77 and future designs will push the experience in premium smartphones and tablets to new highs in the coming years.
