GX4002 Datasheet, PDF (36/74 Pages) Gennum Corporation – Dynamic on-chip power management control

To ensure proper operation of the PRBS7 generator, PRBSGENSTART needs to be set
HIGH and then LOW once after the generator is powered-up through PDPRBSGEN.
To ensure proper operation of the PRBS7 checker, PRBSCHKCLEARERR needs to be set
HIGH and then LOW after application of valid PRBS7 pattern to clear any spurious
errors. PRBSCHKSTATUS, may be polled to check for errors flagged by the checker.
The PRBS generator can be configured to apply the PRBS7 pattern to SDO1 or SDO0 or
internally. Apply to either the Ch1 or the Ch0 CDR for retiming before transmitting out
through SDO. Controls LBCH1INPRBSGEN, LBCH1OUTPRBSGEN,
LBCH0INPRBSGEN and LBCH0OUTPRBSGEN determine the path of the PRBS pattern.
Both PRBS generator and checker can be clocked off either the Ch0 or Ch1 recovered
clocks independently through controls PRBSGENCLKSEL and PRBSCHKCLKSEL. The
PRBS checker automatically selects retimed data from the CDR which is chosen to
provide its clock through PRBSCHKCLKSEL.
3.6.2 Eye Monitor & Peak Detector
The GX4002 has built-in eye monitors in both the horizontal and vertical direction for
the inner eye. These eye monitors are available for both Ch1 and Ch0 paths. In addition,
both Ch1 and Ch0 inputs have peak detectors available to provide outer eye
information. The information from these monitors can be used to indicate if the input to
the module has degraded. These features can be used during mission mode.
Figure 3-19 shows where the eye monitoring functions are implemented:
SDI0
EQ
Ch0 CDR
DR
Vertical Eye
Monitor,
Peak Detect
Horizontal
Eye Monitor
SDI1
LA
Ch1 CDR
DR
SDO0
SDO1
Figure 3-19: Eye Monitor Implementation
The vertical eye monitor outputs a value proportional to the inner eye opening. The
output of the eye monitor can be sampled and read out digitally through the ADC (see
Section 3.7.1). The acquisition time for the eye monitor is approximately 10ms.
The peak detector outputs a value proportional to the outer eye amplitude. The output
of the peak detector can be sampled and read out digitally through the ADC. The
acquisition time is approximately 10ms.
The horizontal eye monitor outputs a value that is proportional to the horizontal eye
opening, as shown in Figure 3-20 below. The output of the horizontal eye monitor can
be sampled and read out digitally through the ADC. The acquisition time is
approximately 10ms.
GX4002 2x2 14.025Gb/s Crosspoint Switch with Trace
Equalization and Output De-Emphasis
Data Sheet
55972 - 0
March 2012
36 of 74
Proprietary & Confidential