Fujitsu Laboratories Develops Multi-Channel High-Speed Transceiver Circuit for High-Speed Blade Server Performance

Kawasaki, Japan and Sunnyvale, U.S., February 12, 2009

Fujitsu Laboratories Limited and Fujitsu Laboratories of America, Inc. today announced the development of a power-efficient and compact multiple-channel high-speed transceiver circuit, that enables high-speed transmission at 10 gigabits-per-second (10Gbps) when used in backplanes⁽¹⁾ which are circuit boards that act as transmission conduits of blade servers, which are high-performance servers that combine several servers. Compared to conventional technology, this novel backplane transceiver circuit would require only one-fourth (1/4) the power consumption and just half the area, to act as transmission conduits to enable 4-channel 10Gbps transmission in backplanes. It is anticipated that the new transceiver circuits will be employed in backplanes to meet the increasing need for blade server systems featuring high-density packaging, high-speed transmissions, and lower power consumption.

Details of this technology were presented at the IEEE International Solid-State Circuits Conference 2009 (ISSCC 2009), held in San Francisco from February 8 to February 12 (Presentation 10.5).

Background

Blade servers - in which the basic components of a server, such as the CPU and memory, are mounted on a bare circuit board in server blades and then installed into a server system comprised of multiple server blades - have become a popular way to design IT systems to reduce space requirements and enable efficiencies in operations. In order for blade servers to achieve superior performance, technologies to enable the backplane - which is a communications circuit board connecting multiple server blades - to achieve high-speed transmissions of 10Gbps, and technologies to accelerate those transmissions through multiple channels are being developed (Figure 1). In recent years, there is growing interest in energy-efficient and higher-density IT equipment to achieve "Green IT"; in addition, for high-speed transceiver circuits in the circuit boards ("switch blades") that execute transmissions between server blades, there is as well demand for higher density and power savings along with higher performance.

Technological Challenges

In order to employ high-speed transceiver circuits that handle 10Gbps transmissions on the backplane, key issues that must be overcome include compensating for transmission losses that occur in the backplane, and reduction of noise attributable to crosstalk and reflections⁽²⁾.
With conventional high-speed transceiver circuits that compensate for transmission losses without amplifying noise, the use of multi-stage equalizer circuits was required to achieve sufficient compensation for transmission, thus increasing both required power and area. Thus, it had been difficult to realize high-speed multi-channel transceiver circuits that enable server systems featuring high performance, energy efficiency, and high densities.

Newly Developed Technology

Taking advantage of the characteristics of two different kinds of equalizer circuits⁽³⁾, Fujitsu Laboratories has developed a new receiver equalizer control method that minimizes signal distortion resulting from transmission losses, and has built it into the receiver equalizer circuit. This receiver equalizer circuit supports 10Gbps transmissions over multiple channels and obviates the need for multi-stage equalizer circuits, resulting in numerous benefits: faster speed, lower power consumption, the ability to provide the loss-compensation necessary for backplane transmissions, and noise reduction. The new receiver equalizer control method also obviates the matrix multiplication needed in previous methods, as it can work using only scalar addition and subtraction, thus enabling simpler logic circuits which can be implemented even on a small area.

Results

By employing the aforementioned technology and 90nm CMOS technology, Fujitsu Laboratories developed a 4-channel high-speed transceiver circuit capable of achieving 10Gbps backplane transmission speeds, and verified that backplane transmission speeds of 10Gbps were achieved (Figure 2).

Compared to conventional high-speed transceiver circuits that do not use this new technology from Fujitsu Laboratories, the receiver circuit portion of the new transceiver circuit requires approximately just half (1/2) the space and runs on just one-fourth (1/4) the power.

As a result of these new technologies, there is sufficient space for the transceiver circuit to have multiple channels, thus enabling the implementation of 4 channels and thereby quadrupling the performance. Because backplane transmissions of 10Gbps can be achieved on multiple channels, effective transmission speeds in excess of 10Gbps are enabled.

Future Developments

By taking advantage of the integration of multiple channels, and by embedding the new transceiver circuit into LSIs to enable high-performance switches, it is anticipated that the new transceiver circuit utilizing the aforementioned technology will be employed for blade server systems requiring high-density packaging and high-speed transmissions. The technology can also be applied to forthcoming 40Gbps Ethernet, for server systems that feature higher performance, higher density packaging, and lower power requirements.