Gregory A. Northrop

Design methodology for the S/390 parallel enterprise server G4 microprocessors

This paper describes the design methodology employed in the design of the S/390® Parallel Enterprise Server G4 microprocessors. Issues of verifying design metrics of area, power, noise, timing, testability, and functional correctness are discussed within the context of a transistor-level custom design approach. Practical issues of managing the complexity of a 7.8-million-transistor design and encouraging design productivity are introduced.

Backend CAD flows for "restrictive design rules"

To meet challenges of deep-subwavelength technologies (particularly 130 nm and following), lithography has come to rely increasingly on data processes such as shape fill, optical proximity correction, and RETs like altPSM. For emerging technologies (65 nm and following) the computation cost and complexity of these techniques are themselves becoming bottlenecks in the design-silicon flow. This has motivated the recent calls for restrictive design rules such as fixed width/pitch/orientation of gate-forming polysilicon features. We have been exploring how design might take advantage of these restrictions, and present some preliminary ideas for how we might reduce the computational cost throughout the back end of the design flow through the post-tapeout data processes while improving quality of results: the reliability of OPC/RET algorithms and the accuracy of models of manufactured products. We also believe that the underlying technology, including simulation and analysis, may be applicable to a variety of approaches to design for manufacturability (DFM).

A semi-custom design flow in high-performance microprocessor design

In this paper we present techniques shown to significantly enhance the custom circuit design process typical of high-performance microprocessors. This methodology combines flexible custom circuit design with automated tuning and physical design tools to provide new opportunities to optimized design throughout the development cycle.

Physical synthesis methodology for high performance microprocessors

Integrated logic synthesis and physical design (physical synthesis) continues to play a very important role in high performance microprocessor design methodologies. In this paper, we present the integrated physical synthesis timing closure methodology used in the current generation microprocessors. Physical synthesis techniques were aggressively used as part of logic and placement optimizations for performance, power and area. The design turn around times were significantly reduced and timing convergence was consistently acheived.

760 MHz G6 S/390 microprocessor exploiting multiple Vt and copper interconnects

The G6 system is a sixth generation CMOS server for the S/390 line of products featuring a 12+2 SMP size and significant frequency improvements obtained through the use of low-Vt devices and copper interconnects. The microprocessor operates at 760 MHz at the fast end of the process distribution. The system ships at 637 MHz in a 12+2 chilled SMP configuration. Measured system performance on the 12 way is 1600 S/390 MIPs, providing over 50% more performance than the G5. This microprocessor uses CMOS7S technology, which has a 0.2 /spl mu/m process. The chip uses 6 levels of copper metal plus an additional layer of local interconnect on a 14.6/spl times/14.7 mm/sup 2/ die with 25M transistors (7M logic/18M array). The power supply is 1.9 V and the chip power is 33 W at 637 MHz.

IBM eServer z900 high-frequency microprocessor technology, circuits, and design methodology

The IBM eServer z900 microprocessor is a seventh-generation zSeries™ (formerly S/390®) CMOS design which has achieved 1.3-GHz operation. This paper describes the 0.18-µm bulk CMOS, seven-level copper metal process and the high-frequency circuit, integration, and design methodologies developed to achieve this operation. The microprocessor was floorplanned to closely mimic the flow of the microarchitecture pipeline and reduce the communication delay overhead between units. Novel circuit techniques were used in the implementation of the arrays and cache hit detection logic to save power and reduce circuit complexity without sacrificing performance. A four-dimensional gate library and novel synthesis algorithms were developed to yield synthesized control implementations with the performance characteristics of a fully custom circuit design.

609 MHz G5 S/399 microprocessor

The IBM G5 system is a fifth-generation CMOS server for the S/390 line of products with functionality improvements such as an instruction branch target buffer (BTB) and an IEEE compliant binary floating-point. The microprocessor operates at 600 MHz at the fast end of the process distribution, although the system is shipped at 500 MHz in a 10+2 SMP configuration. Measured system performance on the 10 way is 1069 S/390 MIPs. This microprocessor uses a 0.25 mum CMOS process. The chip uses 6 levels of metal plus an additional layer of local interconnect and is 14.6times14.7 mm2 with 25 M transistors (7 M logic/18 M array). Power supply is 1.9 V. Chip power is 25 W at 500 MHz

Libraries: LifeJacket or Straitjacket

With the advent of nanotechnologies, the so-called “productivity gap” between the number of transistors we can design and the hundreds of millions we can physically place on a chip is growing. Not only is the complexity increasing in the macrocosm of SoCs and system-level design, it is also exploding at the microcosmic level of wires, transistors and shapes. Time-tomarket, first-time-right and high-performance pressures worsen the situation.

Deep submicron design techniques for the 500 MHz IBM S/390 G5 custom microprocessor

High frequency microprocessor designs require rigorous design guidelines, design methodology advancements, and novel approaches in circuit design style for processors operating in the high megahertz range. Timing closure becomes the single most important design issue, however other design metrics such as area, power and noise need to be given equal consideration within the design cycle. Custom design techniques were used through out the logic circuits and arrays as well as the overall design planning for the 500 MHz microprocessor cycle time.

A 1.1 GHz first 64 b generation 2900 microprocessor

The first 64 b S/390 microprocessor implemented in a 0.18 /spl mu/m, 7-level copper interconnect bulk CMOS process, runs operating system and applications at 1.1 GHz. The frequency is achieved with interconnect width and repeater optimization, selective use of low-Vt devices, tapered library gates, and improved synthesis and circuit tuning algorithms.