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AN1572.0
June 4, 2010
levels are set by positioning jumpers on the appropriate
header as illustrated in Figure 2. For both sets of
headers, DE-A and DE-B can each be set to one of three
values (Vdd, GND, or Floating). Table 1 gives the jumper
positions required to achieve various de-emphasis levels.
As an example, Figure 2 depicts the jumper positions
that set the output de-emphasis level to 3dB
(DE-A = GND and DE-B = Vdd).
Transmit Disable
The ISL35411 provides an independent transmit disable
feature for each of its channels. With this feature, idle
and/or unused channels on the ISL35411 can be made to
enter a low-power standby mode. Entry into this mode is
controlled by each channel's respective TDSBL pin. The
TDSBL-1 pin (for Channel 1) is located at header JP1 on
the north-side of the board. The TDSBL pins for the
remaining channels are located at header JP2 on the
south-side of the board. By using a jumper to tie a given
TDSBL pin to Vdd (as shown in Figure 3), the
corresponding channel on the ISL35411 is disabled.
While disabled, all internal circuitry associated with the
channel is powered down, and the channel is incapable of
driving any high-speed signal applied to its input. If the
TDSBL pin is left floating (no jumper installed), the
respective channel is enabled and is capable of driving
high-speed data.
Baseline Performance
The eye diagrams in Figure 4 show the typical
high-speed performance of the ISL35411DRZ-EVALZ
evaluation board. Figure 4A shows the output of a single
channel at 10.3125Gb/s with no output de-emphasis
(DE level = 0dB). Figure 4B shows the output of a single
channel at 10.3125Gb/s with maximum output
de-emphasis (DE level = 4dB). The output de-emphasis
supplied by the ISL35411 can be used to
pre-compensate the signal for subsequent
frequency-dependent channel loss. Figure 4C shows the
eye diagram of a waveform that has been transmitted
from the output of the ISL35411 with maximum
de-emphasis (DE level = 4dB) across a 22-inch long
trace on an FR408 circuit board. The trace loss at 5GHz is
approximately -8dB. The open eye diagram in Figure 4C
illustrates the channel equalization capabilities of the
ISL35411's output de-emphasis feature.
TABLE 1. JUMPER POSITIONS FOR OUTPUT
DE-EMPHASIS SETTINGS
DE-A
DE-B
DE LEVEL (dB)
No jumper
No jumper
0
No jumper
Jumper to GND
0.6
No jumper
Jumper to Vdd
1.1
Jumper to GND
No jumper
1.6
Jumper to GND
Jumper to GND
2.3
Jumper to GND
Jumper to Vdd
3
Jumper to Vdd
No jumper
4
Vdd A
B
C
GND
DE-A
DE-B
FIGURE 2. JUMPER CONFIGURATION FOR 3dB
OUTPUT DE-EMPHASIS
Vdd A
B
C
GND
TDSBL
FIGURE 3. JUMPER INSTALLED FOR TRANSMIT
DISABLE
FIGURE 4A. 10.3125Gb/s EYE DIAGRAM AT
ISL35411DRZ-EVALZ EVALUATION
BOARD OUTPUT (OUTPUT LEVEL = 0dB)
Application Note 1572
