Carrizo: A High Performance, Energy Efficient 28 nm APU

AMD's 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 APU's 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.