User guide

4
Use a shielded cable to connect the pattern generator's Data Out port and the
error detector's Data In port.
5
Switch to the Pattern panel and press Pattern Select. Select an appropriate
pattern for this test. We use a pure 2^23-1 PRBS segment.
6
For the pattern generator setup you need to specify the logic levels and the bit
rate. Select ECL levels and a clock speed of 1250MHz in this example. This
corresponds to a clock period of 0.8ns. See “Setting up the Pattern Generator
- Concepts ” on page 121 for more information.
7
Set up the error detector so that the input range and the termination matches
the pattern generator's levels:
– Select an Input Range from -2V to 0V
– Set the Data Termination to -2V
– Set the Alignment BER Threshold to 1E-6.
– Set the Clock Setup to Clock Data Recovery to get the error detector's
clock from the incoming data stream.
8
Enable the pattern generator outputs by pressing the 0V (Disable) button.
9
Press Sync Now and then Auto Align to find the optimum sampling point. Check
that the synchronization and the alignment were successful. None of the error
indicators should show red.
The resulting BER should be zero.
How to Execute the Output Levels Measurement
To run the Output Levels measurement:
1
Switch to the Analysis panel and then press the Output Levels icon.
2
Press the Properties button to open the Properties dialog box.
3
On the Parameters tab, set the Sample Threshold parameters to suitable
values that fit to the expected signal levels, for example, -1.85V to -0.85V. Set
the Resolution to 10 mV.
6 Advanced Analysis
266 Agilent J-BERT N4903B High-Performance Serial BERT