User guide

The Serial BERT provides the Interference Channel option J20 to simulate level
variations by adding sinusoidal interference.
For more information see
• “Crosstalk” on page 400
PLL Performance Test
Testing a PLL (or CDR) is not complete until the entire frequency range of the PLL
has been checked under worst-case conditions.
For this purpose, the Serial BERT provides the Jitter Tolerance Characterization
measurement.
For more information see
• “Jitter Tolerance Characterization - Concepts” on page 433
PLL Standards and Compliance Tests
The Optical Internetworking Forum (OIF) as well as other institutions have
proposed standards for testing the performance of data receivers and receiver
circuits in the presence of jitter.
For this purpose, the Serial BERT provides the Jitter Tolerance Compliance
measurement. This measurement is available as an option (option J12) which can
be ordered together with the instrument or retrofitted.
For more information see
• “Jitter Tolerance Compliance - Concepts” on page 446
Understanding the Types of Jitter
The standards for jitter tolerance tests prescribe combinations of certain jitter
types. This section gives an overview of these types.
Random Jitter
Random jitter (RJ) is always present. Resistors, transistors, and other components
generate noise that impacts transmitters and receivers. This kind of jitter has a
Gaussian distribution over time.
Theoretically, the Gaussian distribution stretches from -∞ to +∞. In practice, the
amplitude is defined by the crest factor (p-p amplitude = sigma × crest factor)
Jitter Tolerance Tests 8
Agilent J-BERT N4903B High-Performance Serial BERT 397