GS6150 Datasheet, PDF (25/64 Pages) Gennum Corporation – Automatic or Manual Rate Selection

Table 4-3: Serial Digital Output Swing Settings (Continued)
Register Setting
(See Note 1)
Min
Typ
Max
Units
1000_b
455
605
760
mV
1001_b
490
655
820
mV
1010_b
530
705
880
mV
1011_b
565
755
945
mV
1100_b
600
800
1000
mV
1101_b
630
840
1050
mV
1110_b
670
890
1110
mV
1111_b
700
930
1160
mV
Note:
1. Applicable registers that can be programmed with the values shown above are DDO0_SWING_1G485,
DDO0_SWING_270M, DDO0_SWING_125M, DDO0_SWING_BYPASS, DDO0_SWING_MUTE,
DDO0_SWING_5G94, DDO0_SWING_2G97, DDO1_SWING_1G485, DDO1_SWING_270M,
DDO1_SWING_125M, DDO1_SWING_BYPASS, DDO1_SWING_MUTE, DDO1_SWING_5G94, and
DDO1_SWING_2G97
4.5.4 Output De-emphasis
The GS6150 features adjustable output de-emphasis to compensate for PCB dielectric
trace loss. Each output can be independently set to a different de-emphasis setting for
each detected rate through controls found in the DRIVER_CONTROL_REG_1 and
DRIVER_CONTROL_REG_2 registers.
The effect of de-emphasis, illustrated in Figure 4-3, is to attenuate the swing of bits that
do not follow a bit transition (V_DE). The swing of bits that do follow a bit transition (V_nom)
is set by the output swing registers found in Section 4.5.3 and do not depend on the
de-emphasis settings.
Nominal
Swing (V_nom)
De-emphasized
Swing (V_DE)
Data Pattern
0
1
1
1
0
0
De-emphasis = 20 x log (V / V )
10 nom DE
Figure 4-3: De-emphasis Waveform
GS6150
Final Data Sheet
PDS-060127
Rev.2
March 2015
www.semtech.com
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