4.3 A 20nm 2.5GHz ultra-low-power tri-cluster CPU subsystem with adaptive power allocation for optimal mobile SoC performance

This paper describes design features of the high-performance CPU from a heterogeneous tri-cluster, deca-core CPU subsystem incorporated into the Helio X20 mobile SoC for smartphone applications. The SoC is fabricated in a 20nm high-κ metal-gate CMOS, and has a die size of 100mm2. Additional key features of the SoC include: a graphics processor unit, multimedia (including 32MPixel/24fps camera support), and connectivity subsystems integrating 802.11ac, GPS, and multistandard cellular modems, featuring LTE FTD/TDD R11 Cat-6 with 20+20 carrier aggregation (300/50Mb/s) DC-HSPA+, TD-SCDMA, Edge, CDMA2000 1x/EVDO Rev. A (SRLTE).