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R
Ports and Attributes
Table 6-15
Table 6-15: TX Driver Ports
Table 6-16
Table 6-16: TX Driver Attributes
Description
Differential Voltage Control
The amplitude of the TX driver's differential swing can be controlled using the
TXDIFFCTRL and TXBUFDIFCTRL ports. As shown in
TXDIFFCTRL controls the drive strength of the main pad driver and the pre-emphasis pad
driver.
possible settings for the port.
percentage of overall TX swing.
Virtex-5 RocketIO GTP Transceiver User Guide
UG196 (v1.3) May 25, 2007
defines the TX driver ports.
Ports
MGTTXN0
MGTTXN1
MGTTXP0
MGTTXP1
TXBUFDIFFCTRL0[2:0]
TXBUFDIFFCTRL1[2:0]
TXDIFFCTRL0[2:0]
TXDIFFCTRL1[2:0]
TXPREEMPHASIS0[2:0]
TXPREEMPHASIS1[2:0]
defines the TX driver attributes.
Attribute
TX_DIFF_BOOST0
TX_DIFF_BOOST1
Table 6-17
shows the differential output voltage that results from each of the
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Clock
Dir
Domain
TXN and TXP are the differential
complements of each other forming a
differential transmitter output pair. These
Out
TX Serial
ports represent pads, so their locations
(Pad)
Clock
must be constrained (see
"Implementation"), and they must be
brought to the top level of the design.
Controls the strength of the pre-drivers.
This port should be tied to the same value
In
Async
as the TXDIFFCTRL port for the
transceiver.
Controls the transmitter differential
output swing.
In
Async
approximate differential voltage swing
that results from each setting.
Controls the relative strength of the main
In
Async
drive and pre-emphasis as shown in
Table
Description
Changes the strength of the TX driver and pre-emphasis buffers.
When set to FALSE, the pre-emphasis percentage is boosted or
increased. See
Table 6-18, page 114
and pre-emphasis values.
Overall differential swing is reduced when TX_DIFF_BOOST is
TRUE (default setting).
Table 6-18
shows the expected transmitter pre-emphasis a
Configurable TX Driver
Description
Chapter 4,
Table 6-18
shows the
6-18.
for nominal differential swing
Figure 6-14, page
112,
113
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