Stephen Douglas Weitzel

POWER7™, a Highly Parallel, Scalable Multi-Core High End Server Processor

This paper gives an overview of the latest member of the POWER™ processor family, POWER7™. Eight quad-threaded cores, operating at frequencies up to 4.14 GHz, are integrated together with two memory controllers and high speed system links on a 567 mm die, employing 1.2B transistors in a 45 nm CMOS SOI technology with 11 layers of low-k copper wiring. The technology features deep trench capacitors which are used to build a 32 MB embedded DRAM L3 based on a 0.067 m DRAM cell. The functionally equivalent chip transistor count would have been over 2.7B if the L3 had been implemented with a conventional 6 transistor SRAM cell. (A detailed paper about the eDRAM implementation will be given in a separate paper of this Journal). Deep trench capacitors are also used to reduce on-chip voltage island supply noise. This paper describes the organization of the design and the features of the processor core, before moving on to discuss the circuits used for analog elements, clock generation and distribution, and I/O designs. The final section describes the details of the clocked storage elements, including special features for test, debug, and chip frequency tuning.

A Resonant Global Clock Distribution for the Cell Broadband Engine Processor

Resonant clocking techniques show promise in reducing global clock power and timing uncertainty (skew and jitter). By resonating the large global clock capacitance with an inductance, the energy used to charge the clock node each period can be recycled within the LC tank network, resulting in lower clock power. Additional power savings are realized by reducing the strength of clock drivers because only losses need to be overcome at resonance. Skew and jitter are improved due to the bandpass characteristic of the LC network and the use of fewer clock buffering stages. We describe how the Cell Broadband Engine (Cell BE) processor is experimentally transformed to have a resonant-load global clock distribution similar to the one in (Chan et al., 2004).