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For the pattern generator the following rules apply:
• Below 620 Mbit/s, the pattern generator can only be operated with an external
clock source, because the internal clock source can only produce signals higher
than 620 Mbit/s.
• The trigger output cannot be set up to trigger on certain pattern positions or
pattern sequences. If this option is enabled (for example in the user interface),
the trigger is sent once for each pattern, but the bit position cannot be specified.
The option to trigger on the divided clock signal is supported as usual.
• There are restrictions to the available clock to data delay values.
The pattern generator can vary the clock to data delay only within a range of
-750 ps to 750 ps (relative to the clock signal). For frequencies above 666 Mbit/
s, this range is sufficient to cover the complete clock cycle (= 1 unit interval).
For lower frequencies, the valid data delay range is smaller than the clock cycle.
The pattern generator cannot generate signals with a delay outside this range.
Therefore, the data delay cannot be set to all values within the clock cycle.
Clock 500 Mbit/s
Valid Range for
Data Delay
2 ns
Valid Data Delay
0
750 ps
-750 ps
Spread Spectrum Clocking
A Spread Spectrum Clock (SSC) is widely used for reducing the peak
electromagnetic radiation at the nominal clock frequency. With SSC, the clock
pulse is modulated with a relatively low-frequency triangle waveform. This
broadens the clock signal spectrum and reduces the peak energy.
The Serial BERT has a built-in SSC generator. This is a licensed option. For
information on how to enable this feature, see
“Installing Hardware Options -
For more information on SSC, see
“Jitter Setup - Concepts ” on page 404
Bit Rate - Procedures
You can use an external clock source or the Serial BERT's internal clock to control
the bit rate.
Setting up the Pattern Generator
4
Agilent J-BERT N4903B High-Performance Serial BERT
141
Summary of Contents for J-BERT N4903B
Page 1: ...S Agilent J BERT N4903B High Performance Serial BERT User Guide s Agilent Technologies ...
Page 10: ...10 Agilent J BERT N4903B High Performance Serial BERT ...
Page 36: ...1 Planning the Test 36 Agilent J BERT N4903B High Performance Serial BERT ...
Page 60: ...2 Setting up External Instrument s 60 Agilent J BERT N4903B High Performance Serial BERT ...
Page 120: ...3 Setting up Patterns 120 Agilent J BERT N4903B High Performance Serial BERT ...
Page 360: ...6 Advanced Analysis 360 Agilent J BERT N4903B High Performance Serial BERT ...
Page 468: ...8 Jitter Tolerance Tests 468 Agilent J BERT N4903B High Performance Serial BERT ...
Page 524: ...9 Solving Problems 524 Agilent J BERT N4903B High Performance Serial BERT ...
Page 566: ...10 Customizing the Instrument 566 Agilent J BERT N4903B High Performance Serial BERT ...