Guhan Krishnan

Carrizo: A High Performance, Energy Efficient 28 nm APU

AMDs 6th generation “Carrizo” APU, targeted at 12-35 W mobile computing form factors, contains 3.1 billion transistors, occupies 250.04 mm 2 and is implemented in a 28 nm HKMG planar dual-oxide FET technology with 12 metal layers. The design achieves a 29% improvement in transistor density compared to the 5th generation “Kaveri” APU, also a 28 nm design, and implements several power management features resulting in area and power improvements similar to a technology shrink. Increased power density makes meeting the thermal limits required for reliability and power distribution to the APUs processors substantial design challenges. Pre-silicon thermal analysis is used to understand and take advantage of thermal gradients. Adaptive voltage-frequency scaling in the processor core as well as wordline and bitline assist techniques in the L2 cache enable lower minimum voltage requirements.

4.8 A 28nm x86 APU optimized for power and area efficiency

Carrizo (CZ, Fig. 4.8.7) is AMDs next-generation mobile performance accelerated processing unit (APU), which includes four Excavator (XV) processor cores and eight Radeon™ graphics core next (GCN) cores, implemented in a 28nm HKMG planar dual-oxide FET technology featuring 3 Vts of thin-oxide devices and 12 layers of Cu-based metallization. This 28nm technology is a density-focused version of the 28nm technology used by Steamroller (SR) [1] featuring eight 1× metals for dense routing, one 2× and one 4× for low-RC routing and two 16x metals for power distribution.

Energy-Efficient Graphics and Multimedia in 28-nm Carrizo Accelerated Processing Unit

Carrizo is AMDs sixth-generation accelerated processing unit (APU), optimized to deliver performance uplifts and battery-life improvements in thinner and lighter notebook platforms. Its primary goals are to deliver a differentiated gaming and multimedia experience to the end user and to make progress toward AMDs goal of improving energy efficiency in its APUs by 25 times by year 2020. This article describes the new features, low-power architecture, and power management algorithms used to achieve these goals. Carrizo delivered a 63 percent increase in the 3DMark11 benchmark score, a 350 percent increase in video transcoding throughput, a 60 percent reduction in full-screen HD video playback power, and a 50 percent reduction in Windows idle power compared to its predecessor, the Kaveri APU.