Repeaters triple reach of PCI Express Gen-3 Standard
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National Semiconductor has introduced a family of PCI Express (PCIe) Gen-3 (8Gb/s) repeaters that it claims offers unprecedented signal conditioning performance and low power consumption for data centre servers and storage systems.
According to Dave Thompson, platform applications engineer at Intel, PCI Express 3.0 increases the data rate to 8GT/s, allowing the company's next generation desktop and server platforms to meet I/O bandwidth demands of today's applications. "National Semiconductor's PCIe repeaters address the tough signal integrity requirements of PCI-SIG receiver testing and are utilised to compensate for interconnect loss, ensuring an open eye."
The PCIe repeaters passed Gen-3 interoperability testing with Intel server processors and multiple third party PCIe controllers at the PCI-SIG Compliance Workshop, held w/c April 18, 2011. The tests included link training and data transactions in x4, x8 and x16 configurations at Gen-1, Gen-2 and Gen-3 speeds.
Powered by National's third generation SiGe BiCMOS process, the new PCIe repeaters are designed to solve the signal integrity challenges presented by the 8Gb/s Gen-3 data rate. The DS80PCI102, DS80PCI402 and DS80PCI800 are said to accomplish this by providing receive equalisation gain up to 36dB and transmit deemphasis of 12dB to deliver 3x the signal reach and half the power (65mW/channel) of competitive devices.
According to National, the PowerWise repeaters performance enables up to 40in of FR-4 backplane reach to simplify migration from Gen-2 to Gen-3 data rates, making it possible for system designers to use inexpensive, higher loss cable and board interconnects.
The DS80PCI402 enables implementation of x4 PCIe interfaces while the DS80PCI800 is ideal for higher density interfaces such as x8 and x16. The DS80PCI102's x1 interface is suitable for industrial and desktop applications. Each device supports detection and management of the new Gen-3 transmit FIR handshake protocol and PCIe out of band signals, such as transmit idle/beacon and receive detect, without external system intervention.
The DS80PCI800 includes eight channels while the DS80PCI402 features four bidirectional lanes and the DS80PCI102 one bidirectional lane. Each device delivers 65mW per channel typical power consumption and support a selectable 3.3 or 2.5V single supply voltage with no reference clock required.
The repeaters extend interconnect reach by performing both receive equalisation and transmit de-emphasis on each lane to compensate for channel loss. This allows for maximum flexibility in physical placement within a system. A flow through pin out minimises internal device jitter and allows for easy board layout. All three repeaters allow powering down of unused channels, and apply signal conditioning settings via pin selection, SMBus (I2C compliant) or directly from an EEPROM.
