Optional Configurable Rx Linear Equalization; Rx Oob/Beacon Signaling; Overview - Xilinx Virtex-5 RocketIO GTP User Manual

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Optional Configurable RX Linear Equalization

High-speed serial traces and connections typically attenuate high-frequency signals more
than low-frequency signals. As a result, high-frequency data passing through a channel
tends to get distorted as the high-frequency components of the signal lose more power
than the low-frequency components.
The GTP receiver includes an linear equalizer circuit that can be used to compensate for
signal distortion on the line due to high-frequency attenuation. To activate the equalizer,
the active-Low RXENEQB is driven Low. The equalizer is disabled by driving RXENEQB
High.
While the equalizer is active, it uses a separate receive buffer to filter out low-frequency
signals and capture only the high-frequency components of incoming data. This signal is
then mixed with the input captured by the regular receive buffer to produce a signal with
amplified high-frequency components. The ratio of the signal from the high-frequency
buffer and the regular (wideband) buffer is controlled by the RXEQMIX port.
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The cutoff frequency for the high-frequency buffer is controlled by the RXEQPOLE port.
By moving the pole of the filter in the high-frequency path, the frequency range of the
high-frequency buffer can be controlled.
RXEQPOLE.

RX OOB/Beacon Signaling

Overview

The GTP_DUAL provides support for decoding the out-of-band (OOB) sequences
described in the Serial ATA (SATA) and beaconing is described in the PCI Express
specifications. An overview of OOB signaling and how it is used in these protocols can be
found in
Support for SATA OOB signaling consists of the analog circuitry required to decode the
OOB signal state and state machines to decode bursts of OOB signals for SATA COM
sequences (COMRESET, COMWAKE, and COMINIT).
The GTP_DUAL supports PCI Express based beacons by using interface signals defined in
the PHY interface for the PCI Express (PIPE) specification. The FPGA logic decodes the
beacon sequence.
Virtex-5 RocketIO GTP Transceiver User Guide
UG196 (v1.3) May 25, 2007
shows the different ratios.
Appendix B, "OOB/Beacon Signaling."
www.xilinx.com
RX OOB/Beacon Signaling
Table 7-1 shows the possible settings for
Table 7-1,
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