SigmaRAM consortium announces fast SRAMs

The SigmaRAM Consortium has announced the availability of high-speed 18-Mbit synchronous SRAMs with a data throughput rate of up to 24 Gb/s at a 333-MHz clock speed.

The SigmaRAM Consortium has announced a multi-year product roadmap, datasheets, and first availability of JEDEC-standard high-speed 18-Mbit synchronous SRAMs that can sustain a data throughput rate of up to 24 gigabits per second (Gb/s) at a 333-MHz clock speed.

Consortium members participating in the SigmaRAM industry roadmap include GSI Technology, Integrated Silicon Solution Inc., Mitsubishi Electric Corporation, Sony Electronics, and Toshiba Corporation.

Members of the SigmaRAM Consortium have agreed on what they believe to be the industry’s first and only open-standard for multiple-sourced, high-speed synchronous SRAMs tailored to the networking and telecom markets (the SigmaRAM devices). The members of the consortium intend to independently develop and market products adhering to this standard.

To demonstrate the viability of SigmaRAM devices for networking and telecom uses, the consortium has worked closely with Xilinx to recently interface the SigmaRAM devices with the Xilinx Virtex-II platform FPGA (field programmable gate array), using the system I/O features of this component and the timing capabilities of both devices.

‘This new interface enables the designer to take full advantage of both the high-speed and data alignment capabilities of the Virtex-II I/Os while implementing all access protocol functions,’ said Jean-Louis Brelet, manager, applications engineering, Xilinx Advanced Products Group.

‘For the last decade, the SRAM market has been dominated by cache memory applications,’ said Bob Merritt, vice president, Semico Research, an analyst with expertise in networking and PC architectures. ‘However today, networking and communications have clearly replaced PCs as the main drivers for new concepts and technologies. SRAMs are now required to deliver much higher densities, lower power consumption, easier PC board routing, and new SRAM interface protocols for networking.’

‘SigmaRAM supports the wide bus structures and fast random-address cycle times that traditional SRAMs cannot handle effectively,’ added Merritt. ‘The full support of the SigmaRAM Consortium will go far in assuring customers of a solid supply of material and a strong roadmap to future products.’

SigmaRAM devices consolidate many different SRAM architectures and operation modes into a single product family.

SigmaRAM devices come in two architectures – common I/O and separate I/O. These devices offer the widest data bus of 72 bits in the common I/O single data rate (SDR) architecture, and are the first to offer 36 bits in the separate I/O architecture.

SigmaRAM devices operating at 333 MHz are capable of sustaining up to 24Gb/s data throughput with entirely random addressing. Common I/O versions share one data bus, yet incur no penalty when alternating between reads and writes. Separate I/O versions feature independently optimized read and write buses. Both variations offer double data rate (DDR) architectures that can sustain similar throughput with fewer pins.

SigmaRAM devices use a 209-pin, ball grid array (BGA) package that provides twin benefits of scalability from 18-Mbit to 144-Mbit densities and ease in routing over traditional SRAM packaging for workstation and server applications.

Additional features of SigmaRAM devices include low-power consumption resulting from a 1.8-volt supply voltage and JEDEC-standard 1.5- and 1.8-volt interfaces, a source-synchronous interface (via echo clocks), programmable chip enables for easy depth expansion, programmable output drive strength, late and double late write modes, pipeline read mode, coherent reads and writes, byte-write operation, IEEE 1149.1 JTAG boundary-scan testability, clamshell pinouts, and burst mode.

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