Jeffrey S. Zimmerman

A Resonant Global Clock Distribution for the Cell Broadband-Engine Processor

Resonant clock distributions have the potential to save power by recycling energy from cycle-to-cycle while at the same time improving performance by reducing the clock distribution latency and filtering out non-periodic noise. While these features have been successfully demonstrated in several small-scale experiments, there remained a number of concerns about whether these techniques would scale to a product application. By modifying the Cell broadband engine processor to incorporate a large resonant global clock network, power savings with full functionality is demonstrated over a 20% range in clock frequencies, and a 6-8 Watt power savings at 4 GHz. This was achieved by changing one wiring level and adding an additional thick copper level to create inductors and capacitors.

A low-power RISC microprocessor using dual PLLs in a 0.13 /spl mu/m SOI technology with copper interconnect and low-k BEOL dielectric

Microprocessors achieving clock frequencies >1 GHz for mobile applications require solutions to maintain long battery life. Circuit and architecture solutions for dynamic frequency switching between multiple PLLs, DC power reduction methods, and impact of low-k dielectric on timing and power are discussed.

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).

A 1 MB, 100 MHz integrated L2 cache memory with 128b interface and ECC protection

Several cache-DRAMs have been reported, but all require multiple chips to implement an L2 cache system. The advent of 20 ns, 16 Mb DRAM technology has made a high-speed single-chip 1MB cache possible, replacing multiple SRAM and logic modules, saving board space and reducing power. Multichip-module (MCM) packaging further optimizes the electrical characteristics of the processor-cache connection. An in-line level-2 1 MB cache chip that has DRAM density contains high-speed SRAM and MCM technology.

PowerPC 970 in 130 nm and 90 nm technologies

A 64 b PowerPC microprocessor is introduced in 130 nm and redesigned in 90 nm SOI technology. PowerPC 970 implements a SIMD instruction set with 512 kB L2 cache. It runs at 2.0 GHz with a 1.0 GHz bus in 130 nm. The 90 nm design features PowerTune for rapid frequency and power scaling and electronic fuses.

A 64-bit microprocessor in 130-nm and 90-nm technologies with power management features

The first two members in a family of 64-bit superscalar microprocessors are presented. The 130-nm processor, which was introduced first, offers 5-way instruction dispatch, support for 4-way integer and floating-point single-instruction multiple-data (SIMD) operations, a 512-kB second level (L2) cache, and a high-speed external bus. The 90-nm processor is a technology remap of the 130-nm design. It retains the features of the 130-nm processor and adds others, including a new power management facility. The architecture, device characteristics, power management, and thermal details of these two processors are described. In addition, the dataflow layout, aspects of the circuit design, clocking, and timing are discussed.