R31DS0036EU0300 MAY 20, 2021

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©2021 Renesas Electronics Corporation

8SLVP1212 Datasheet

Additive Phase Jitter (3.3V at 122.88MHz)

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 measurement equipment. The

noise floor of the equipment can be higher or lower than the noise

floor of the device. Additive phase noise is dependent on both the

noise floor of the input source and measurement equipment.

Measured using a Wenzel 122.88MHz Oscillator as the input source.

Offset from Carrier Frequency (Hz)