GS3140 Datasheet, PDF (18/40 Pages) Semtech Corporation – Multi-Rate Adaptive 3G SDI Equalizer

Table 4-3: De-emphasis Levels
De-emphasis Level
000_b
001_b
010_b
011_b
100_b
101_b
110_b
111_b
Operating Level
0
1.2
2.5
4.1
6.0
8.5
12.0
18.1
Units
dB
dB
dB
dB
dB
dB
dB
dB
4.9.2 Output Common Mode Voltage
The output common mode voltage level (V_CMOUT) is a function of the output voltage
swing, the output driver supply voltage (V_{CC_O}) and how the transmission line is
terminated. If the outputs are terminated through 50Ω resistors to a voltage V_TERM
equal to V_{CC_O}, as shown in Figure 4-2 below, the output common mode voltage is
given by the following expression:
V_CMOUT
=
V_C
C
_O
–
Δ_-----V_{----D---D---O--}
4
If the differential outputs are terminated across a 100Ω resistor, as shown in Figure 4-3
below, the output common mode voltage is given by the following expression:
V_CMOUT
=
V_C
C
_O
–
Δ_-----V_{----D---D---O--}
2
Equation 4-1
Equation 4-2
GS3140 _{VCC_O}
50Ω
50Ω
DDO
DDO
50Ω
50Ω
V V _TERM
TERM
50Ω 50Ω
GS3140 _{VCC_O}
50Ω
50Ω
DDO
50Ω
DDO
50Ω
100Ω
Figure 4-2: 50Ω Termination to V_TERM
Figure 4-3: 100Ω Parallel Output Termination
GS3140
Final Data Sheet
PDS-060939
Rev.1
May 2015
www.semtech.com
18 of 40
Semtech
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