6©2016 Integrated Device Technology, Inc Revision A February 5, 2016
8S58035I Data Sheet
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
have 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.
Measured using a Rohde & Schwarz SMA100A as the input
source.
Additive Phase Jitter @ 622.08MHz
12kHz to 20MHz = 47fs (typical)
SSB Phase Noise dBc/Hz
Offset from Carrier Frequency (Hz)