Agilent Technologies DisplayPort Manuel d'utilisateur télécharger pdf (Page 42)

Agilent Technologies, Inc.

DisplayPort Test Implementation Group 42 Agilent J-BERT N4903B & 90000A/X/Q Series Sink Draft2

C. Appendix: RBR ISI and Eye Height Measurements

According to PHY CTS 1.2b the RBR stress test signal is measured at TP3 before an equalizer. The

required ISI component is 570mUI. The measurement methods used for HBR2 and HBR cannot be

applied in this case since the ISI creates problems for the clock recovery algorithms of the scope. The

following sections describe alternative measurement methods. The measurements do not use clock data

recovery but a clock or trigger signal provided by J-BERT instead. Therefore SSC should be deactivated

for the measurements.

RBR ISI Measurement

ISI will be measured indirectly by using eye opening or jitter

measurements with ISI and without ISI.

The delta of the two measurements is jitter caused by ISI. To measure the eye opening without ISI a clk/2

pattern, 1010, is used. The eye opening measurement with ISI is done using a PRBS 2

-1. All jitter

sources are turned off on J-BERT. Amplitude for the data signal above 500mV

diff

is recommended for this

measurement. The measurement should be performed on the differential data signal at TP3.

BERT based ISI Measurement for RBR

The J-BERT’s Output Timing Measurement can be used to determine the eye opening or phase margin

for a desired BER level. Since a PRBS 2

-1 is a very short pattern a BER level of 10

-6

is more than

sufficient.

Figure 39: J-BERT Output Timing based ISI measured for RBR

The ISI is determined as the delta of the two phase margin measurement, 915mUI – 336mUI = 579mUI.

This measurement requires a BERT error detector and cannot be done on J-BERT options G07 and G13.

1 2 ... 37 38 39 40 41 42 43 44 45 46 47 ... 55 56

Pas de commentaire

Agilent Technologies DisplayPort Manuel d'utilisateur Page 42