8©2016 Integrated Device Technology, Inc Revision B November 16, 2016
831724 Datasheet
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.
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 Rohde & Schwarz SMA
100A. Phase noise is measured using an Agilent E5052A Signal
Source Analyzer.
SSB Phase Noise dBc/Hz
Offset from Carrier Frequency (Hz)
Additive Phase Jitter @ 100MHz
12kHz to 20MHz = 0.357ps (typical)
