Hwa-Joon Oh

The vector floating-point unit in a synergistic processor element of a CELL processor

The floating-point unit in the synergistic processor element of the 1st generation multi-core CELL processor is described. The FPU supports 4-way SIMD single precision and integer operations and 2-way SIMD double precision operations. The design required a high-frequency, low latency, power and area efficiency with primary application to the multimedia streaming workloads, such as 3D graphics. The FPU has 3 different latencies, optimizing the performance critical single precision FMA operations, which are executed with a 6-cycle latency at an 11FO4 cycle time. The latency includes the global forwarding of the result. These challenging performance, power, and area goals were achieved through the co-design of architecture and implementation with optimizations at all levels of the design. This paper focuses on the logical and algorithmic aspects of the FPU we developed, to achieve these goals.

The circuit design of the synergistic processor element of a CELL processor

A 32b 4-way SIMD dual-issue synergistic processor element of a CELL processor is developed with 20.9 million transistors in 14.8mm/sup 2/ using a 90nm SOI technology. CMOS static gates implement the majority of the logic. Dynamic circuits are used in critical areas, occupying 19% of the nonSRAM area. ISA, microarchitecture and physical implementation are tightly coupled to achieve a compact and power efficient design. Correct operation has been observed up to 5.6GHz at 1.4V supply and 56/spl deg/C.