Agilent Technologies J-BERT N4903B, User Manual, Page: 137 / 572

Half Rate Clocking and Clock Duty Cycle
A checkbox allows to enable half rate clocking: the clock at the clock output runs
at half the bit rate. In half rate clocking mode, the duty cycle of the clock can be
adjusted in the range of 40 to 60%.
Xover
This text field allows manual entry of the data's crossover percentage, and displays
the current value. To modify the value, click inside the text field and enter the
desired value directly with the numeric keyboard or use the front panel knob to
fine-tune the value.
Data Polarity Inverted
Select this checkbox to invert the logic of both data outputs (Data Out and Aux
Data Out).
Data, Aux Data, Clock and Trigger/Ref Clock Logic Levels
You can quickly set up an output signal that is compatible with your device by
selecting a logic family from the
Logic Level
list.
Select the logic family you want to use for the Data, Aux Data, Clock and Trigger/
Ref Clock outputs. When you select a family, the corresponding signal voltage
levels and the
Termination
for this family is automatically selected.
N O T E
When you select Custom, there are no changes in the expected terminations.
See “Understanding how the Serial BERT Uses Logic Families and Terminations”
on page 128 for additional information.
Terminations for Data, Aux Data, Clock and Trigger/Ref Clock
Use the Termination checkboxes to toggle between true differential DC coupling
and center tapped termination. In center tapped mode, you can specify the
termination voltage.
The Termination fields are used to set the termination voltage. When you select
a Logic Level, the terminations are set accordingly. It is recommended that you
keep the default values of the terminations.
See
“Understanding how the Serial BERT Uses Logic Families and Terminations”
on page 128 for additional information.
Setting up the Pattern Generator
4
Agilent J-BERT N4903B High-Performance Serial BERT 137