REVISION 1 09/10/14

7

2.5V DIFFERENTIAL LVDS CLOCK DIVIDER AND FANOUT BUFFER

8T74S208 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.

Typical Phase Jitter at 156.25MHz

The input source is 156.25MHz Wenzel Oscillator.

Offset from Carrier Frequency (Hz)

Additive Phase Jitter: 96fs (typical)