Pre-Cursor Emphasis - Xilinx Virtex-6 FPGA User Manual
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Equation 3-1
emphasis. The value from
Alternatively,
Table 3-16: TX Post-Cursor Settings for Various TX Amplitudes
tx_swing
tx_swing
(mV
)
TX_CFG0_LANE[6:3]
PPD
450
4'b0000
600
4'b0011
700
4'b0101
800
4'b0111
900
4'b1001
1000
4'b1011
1100
4'b1101
1200
4'b1111
Pre-Cursor Emphasis
The override bit has to be set as specified:
•
•
Equation 3-2
emphasis. The value from
⎛
tx_precursor 3:0
----------------------------------------------------------
⎝
ROUND
Alternatively,
Table 3-17: TX Pre-Cursor Settings for Various TX Amplitudes
tx_swing
tx_swing
(mV
)
TX_CFG0_LANE[6:3]
PPD
450
4'b0000
600
4'b0011
700
4'b0101
800
4'b0111
900
4'b1001
1000
4'b1011
1100
4'b1101
1200
4'b1111
Virtex-6 FPGA GTH Transceivers User Guide
UG371 (v2.0) February 16, 2010
can determine the tx_postcursor[3:0] value that provides the required
Equation 3-1
[
]
tx_postcursor 3:0
=
ROUND
Table 3-16
can be used as a guide to setting tx_postcursor[3:0].
TX_PREEMPH_LANE<n>[7:4] = tx_post_cursor
0 dB
1 dB
4'd0
4'd1
4'd0
4'd2
4'd0
4'd2
4'd0
4'd3
4'd0
4'd3
4'd0
4'd3
4'd0
4'd4
4'd0
4'd4
TX_CFG1_LANE<n>[8] = tx_premptap_ovrrd_en = 1'b1
TX_PREEMPH_LANE<n>[3:0] = tx_precursor (see
settings)
can determine the tx_precursor[3:0] value that provides the required
Equation 3-2
[
] 1
⎞
–
1
+
⎠
2
ROUND
=
Table 3-17
can be used as a guide to setting tx_precursor[3:0].
TX_PREEMPH_LANE<n>[3:0] = tx_pre_cursor
0 dB
0.75 dB
–
4'd0
4'd0
4'd3
4'd0
4'd3
4'd0
4'd5
4'd0
4'd5
4'd0
4'd5
4'd0
4'd7
4'd0
4'd7
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has to be within the range 4'd0 to 4'd15.
⎛
⎛
(
(
[
]
)
) 1 10
⎜
⎜
18
+
2 tx_swing 3:0
⎝
⎝
2 dB
3.5 dB
4.5 dB
4'd2
4'd4
4'd6
4'd4
4'd7
4'd9
4'd5
4'd8
4'd10
4'd6
4'd10
4'd12
4'd7
4'd11
4'd14
4'd7
4'd12
4'd15
–
4'd8
4'd14
–
4'd9
4'd15
has to be within the range 4'd0 to 4'd15.
⎛
⎛
(
(
[
]
)
) 1 10
⎜
⎜
18
2 tx_swing 3:0
+
⎝
⎝
1.5 dB
2.5 dB
4'd5
4'd7
4'd7
4'd11
4'd7
4'd13
4'd9
4'd15
–
4'd11
–
4'd11
–
4'd13
–
4'd15
TX Configurable Driver
(
)
- Emphasis dB
⎞
⎞
------------------------------------------- -
20
⎟
⎟
–
–
1
⎠
⎠
Equation 3-1
6 dB
7 dB
8dB
4'd7
4'd8
4'd9
4'd11
4'd12
4'd14
–
4'd13
4'd15
–
–
4'd15
–
–
–
–
–
–
–
–
–
–
–
–
Table 3-15
for pre-cursor control
(
)
- Emphasis dB
⎞
⎞
------------------------------------------- -
20
⎟
⎟
1
–
–
⎠
⎠
Equation 3-2
3.5 dB
4.5 dB
4'd10
4'd13
–
4'd13
–
–
–
–
–
–
–
–
–
–
–
–
9dB
4'd10
4'd15
–
–
–
–
–
–
6 dB
4'd15
–
–
–
–
–
–
–
101
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