Agilent Technologies J-BERT N4903B, User Manual, Page: 128 / 572

N O T E
Note that the delay is on Data and Aux Data.
Crossover is the voltage level where the overlapped rising and falling edges of the
logic levels intersect. This adjustment varies the widths of the logic highs and lows.
The following figure shows examples of crossover at 50 %, 80 %, and 20 %:
Understanding how the Serial BERT Uses Logic Families and
Terminations
The clock and data inputs of your device have load impedances (or terminations).
Clock and data terminations refer to the voltage levels at the end of these loads.
These voltage levels are related to the logic family of your device. Your device
should usually only receive signals that are compatible with its termination voltage
and logic family.
When you change a logic family for the Data, Aux Data, Clock or Trigger/Ref Clock
outputs, the termination voltage normally associated with the logic family is
automatically selected. This is assumed to be the termination of your device, and
will be used to determine the actual output voltage levels of the pattern generator.
C A U T I O N
If you manually change the termination, a warning message is shown, indicating
that the termination is not typically appropriate for the logic family. If you answer
No
, the warning message closes with no changes to the terminations. If you answer
Yes
, the data termination voltage is applied and the Logic Level is changed to
CUSTOM.
See also “Why Incorrect Terminations Could Damage Your Device” on page 129 .
4
Setting up the Pattern Generator
128 Agilent J-BERT N4903B High-Performance Serial BERT
Crossover