GS3490 Datasheet, PDF (18/22 Pages) Semtech Corporation – Configurable Adaptive Cable Equalizer/Cable Driver

5. Application Information
5.1 Typical Application Circuit
4.7µF
75Ω
VCC
SDI/O
VCC
8.2nH
75Ω
10nF
8.2nH
75Ω
7.5nH
75Ω
4.7µF
100Ω
1µF
1µF
137Ω
U2
2
SDO
3
SDO
6
SDI
7
SDI
9
AGC+
VCC
Note: AC-coupling capacitors may be required on DDI/DDI and DDO/DDO
when interfacing to devices with incompatible common mode voltages.
750Ω
470nF
10
AGC-
27 _RSET
28
EQ_DISABLE
29 _{CD_ENABLE}
8
EQ_GAIN_SEL
13 _{EQ_BYPASS}
14 _{EQ_SQ_ADJ}
15 _{EQ_OP_CTL}
16
CD_SD_EN
10nF 10nF 10nF 10nF
DDI ¹⁸
DDI ¹⁹
GS3490
DDO 22
DDO 23
30
CD
Figure 5-1: GS3490 Typical Application Circuit
5.2 PCB Layout
Special attention must be paid to component layout when designing Serial Digital
Interfaces for HDTV. A FR-4 dielectric can be used, however, controlled impedance
transmission lines are required for PCB traces longer than approximately 1cm. Note the
following PCB artwork features used to optimize performance:
• PCB trace width for 3Gb/s rate signals is closely matched to SMT component width
to minimize reflections due to change in trace impedance.
• High-speed traces are curved to minimize impedance changes.
Cutouts in the inner layers should be used under the GS3490 input and output
components to minimize parasitic capacitance. For more detail on this and other layout
recommendations, please refer to A Guide For Designing With Semtech's 3G-SDI
Equalizers (Doc ID: GENDOC-055280).
GS3490
Final Data Sheet
GENDOC-058568
Rev. 1
April 2014
www.semtech.com
18 of 22
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