DS40MB200_14 Datasheet, PDF (10/20 Pages) Texas Instruments – Dual 4.0 Gbps 2:1/1:2 CML Mux/Buffer with Transmit Pre-Emphasis and Receive Equalization

DS40MB200
SNLS144I – JUNE 2005 – REVISED MARCH 2013
APPLICATION INFORMATION
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The DS40MB200 input equalizer provides equalization to compensate about 5 dB of transmission loss from a
short backplane transmission line. For characterization purposes, a 25-inch FR4 coupled micro-strip board trace
is used in place of the short backplane link. The 25-inch microstrip board trace has approximately 5 dB of
attenuation between 375 MHz and 1.875 GHz, representing closely the transmission loss of the short backplane
transmission line. The 25-inch microstrip is connected between the pattern generator and the differential inputs of
the DS40MB200 for AC measurements.
Trace Length
25 inches
Finished Trace
Width W
8.5 mil
Separation between
Traces
11.5 mil
Dielectric Height H
6 mil
Dielectric Constant
ε_R
3.8
Loss Tangent
0.022
Data eye from pattern generator
Data eye after 25-inch FR4 trace
Data eye after DS40MB200
50 ps/DIV
50 ps/DIV
50 ps/DIV
Pattern
Generator, 4 Gb/s
D+
D-
27-1 pattern
25-inch FR4
board trace
DS40MB200
IN+
IN-
EQ
R
PE=0dB
M
OUT+
U
D
X
OUT-
40-inch
FR4 trace
50 ps/DIV
Figure 7. Data Input and Output Eye Patterns with Driver Set to 0 dB Pre-emphasis
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