ICS831721I Datasheet, PDF (6/17 Pages) Integrated Device Technology – Differential Clock/Data Multiplexer

ICS831721I Data Sheet
DIFFERENTIAL CLOCK/DATA MULTIPLEXER
Additive Phase Jitter
The spectral purity in a band at a specific offset from the fundamental
compared to the power of the fundamental is called the dBc Phase
Noise. This value is normally expressed using a Phase noise plot
and is most often the specified plot in many applications. Phase noise
is defined as the ratio of the noise power present in a 1Hz band at a
specified offset from the fundamental frequency to the power value of
the fundamental. This ratio is expressed in decibels (dBm) or a ratio
of the power in the 1Hz band to the power in the fundamental. When
the required offset is specified, the phase noise is called a dBc value,
which simply means dBm at a specified offset from the fundamental.
By investigating jitter in the frequency domain, we get a better
understanding of its effects on the desired application over the entire
time record of the signal. It is mathematically possible to calculate an
expected bit error rate given a phase noise plot.
Additive Phase Jitter @ 100MHz
12kHz to 20MHz = 0.314ps (typical)
Offset from Carrier Frequency (Hz)
As with most timing specifications, phase noise measurements has
issues relating to the limitations of the equipment. Often the noise
floor of the equipment is higher than the noise floor of the device. This
is illustrated above. The device meets the noise floor of what is
shown, but can actually be lower. The phase noise is dependent on
the input source and measurement equipment.
The source generator is the Rhode & Schwarz SMA 100A Signal
Generator 9kHz – 6GHz. Phase noise is measured with the Agilent
E5052A Signal source Analyzer.
ICS831721AGI REVISION A AUGUST 19, 2011
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©2011 Integrated Device Technology, Inc.