Product:
PCIe Gen2 ReDriver
TM
Signal Conditioners
Part Numbers:
PI2EQX5804, PI2EQX5864
Signal Integrity Challenges for Gen2 PCIe
Signals
The 5.0Gbps Gen2 revision of PCIe imposes tight
constraints on system and PCB design. When using today’s
typical PCB rules, a 5.0Gbps signal can be routed just 8
inches before signal degradation becomes a concern (half
the distance of 2.5Gbps PCIe Gen-1). To compensate and
allow more reasonable trace lengths, lower impedance
PCBs and larger signal de-emphasis techniques are
suggested. Even when using these techniques, allowable
trace runs are very short for many implementations.
To extend the 5.0Gbps differential trace pair greater
distances and minimize bit error rate, which will increase
system performance and reliability, signal conditioners are
used to restore the original signal quality. A signal with
higher frequency is affected with more signal attenuation
than a signal with lower frequency. The Inter-Symbol-
Interference (ISI) caused by both “Dielectric Loss” and “Skin
Effect” contributes to Pattern Dependent Jitter (PDJ). A
signal conditioner positioned in the data path can adjust
signal levels based on equalization and de-emphasis
techniques, so that the eye-pattern delivered to the receiver
has adequate margins to conform to the PCIe Gen2
standard.
PI2EQX5864
The PI2EQX5864 is a 4-lane (8 differential channels),
5.0Gbps Gen2 PCIe signal conditioner. This device is a
subset of the PI2EQX5804 and features much smaller
packaging. The primary functional difference between these
two devices is in configuration. Configuration of the
PI2EQX5864 can only be made via the I2C interface. Other
than pin configuration, the PI2EQX5864 provides the exact
same features and functionality of the PI2EQX5804. The
PI2EQX5864 is intended as the lowest cost PCIe signal
conditioner solution providing 5.0Gbps performance.
Pericom Solutions
Pericom’s many years of experience in supplying signal
conditioning products has been applied to the Gen2
performance level. Both equalization and de-emphasis
features reverse the “attenuation vs. frequency”, thereby
compensating for degradation and restoring the signals
original source characteristics (signal eye) to the end point
receiver. The PI2EQX5804/64 ReDriver products meet the
protocol requirements for PCIe Gen2 spec.
Figure 1: PI2EQX5804 Block Diagram
PI2EQX5804
The PI2EQX5804 is a 4-lane (8 differential channels),
5.0Gbps PCIe Gen2 signal conditioner. Designed using
Pericom’s proprietary high-speed differential signal
repeater/equalizer technology, the PI2EQX5804 insures
signal integrity over 30 inches of FR4 trace lengths.
Combining the programmable equalization techniques at the
end of a trace (Rx) to compensate for signal attenuation and
the De-emphasis technique to pre-compensate transmission
on outputs allows a signal to traverse through a longer
medium, beyond the standard PCIe limits. PI2EQX5804
features eight CML-differential inputs and output pairs. This
device can Re-Drive four complete PCIe lanes.
Figure 2: Example of PI2EQX5804 in Blade Server
ReDriver on the blades assures signal integrity across the
long backplane.
Page 1 of 2
Pericom Semiconductor Corp.
www.pericom.com
4/22/2008
Key Features & Specifications
PCIe Gen2 differential signal conditioners
5.0Gbps Gen2 PCIe ReDriver
Programmable receiver equalization
Programmable transmitter de-emphasis &
amplitude
Pin-strapped or I2C configuration options
100-Ohm Differential CML I/O’s
Automatic Receiver Detection and control
Loop-back and mux/demux modes
Requires no reference clock
Low power (100mW per channel)
Very low-power stand-by mode
Signal detect & Electrical Idle support per channel
Vcc Operating Range: 1.2V±0.1V
Supports 30 inches of FR4 trace
Packages Offered: Pb-free & Green
100-ball LFBGA – 5804
56-contact TQFN – 5864
Application of ReDriver
TM
Figure 2 shows one example application for PCIeG2
ReDrivers insuring the quality of a signal being passed
across the backplane in a rack server. Figure 3 shows the
input (left) and output (right) data eye of the PCIe Gen2
ReDriver at 5.0Gbps. A good quality signal output is
recovered from a marginal input signal
Figure 3: PI2EQX5804 Data Channel
Applications environment:
Servers (data and telecom)
Storage servers
Test equipment
Desktop PCs with dual-graphics
PCIe cables
PCIe® is a registered trademark of PCI SIG
www.pcisig.org
Page 2 of 2
Pericom Semiconductor Corp.
www.pericom.com
4/22/2008
Embedded System
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