Tx Configurable Driver; Functional Description - Xilinx Virtex-6 FPGA User Manual

TX Configurable Driver

Functional Description

The GTH TX driver is a high-speed, current-mode differential output buffer. To maximize
signal integrity, the TX driver includes these features:
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•
•
Figure 3-3
X-Ref Target - Figure 3-3
PISO
TX Serial Clock =
Data Rate / 2
The transmitter's output level can vary depending on the state of the system. Here are
some common scenarios:
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•
•
Virtex-6 FPGA GTH Transceivers User Guide
UG371 (v2.0) February 16, 2010
Differential voltage swing control
Pre-cursor and post-cursor transmit emphasis
Calibrated termination resistors
is a detailed diagram of the TX driver.
Pre-Driver
Pre-Driver
Pre-Driver
Figure 3-3: TX Driver Structure
Power-up, before configuration
Differential zero: TXP is held Low; TXN is held High.
During configuration
Differential zero: TXP is held Low; TXN is held High.
Reset
Differential zero: TXP is held Low; TXN is held High.
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Pre-Emphasis
Pad Driver
tx_precursor[3:0]
Main Pad Driver
tx_swing[3:0]
Pre-Emphasis
Pad Driver
tx_postcursor[3:0]
TX Configurable Driver
MGTHAVTT_[L,R]
Nominal Nominal
50Ω 50Ω
MGTTXP
MGTTXN
UG371_c3_03_120809
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