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November 20, 2023

8P34S2108 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.

Figure 2. Additive Phase Jitter. Frequency: 156.25MHz, Integration Range: 12kHz to 20MHz = 45fs typical

[f] Defined as skew within a bank of outputs at the same voltage and with equal load conditions.

[g] Output pulse skew is the absolute value of the difference of the propagation delay times:  tPLH - tPHL .

[h] Defined as skew between outputs on different devices operating at the same supply voltage, same frequency, same temperature and with equal

load conditions. Using the same type of inputs on each device, the outputs are measured at the differential cross points.

[i] Common Mode Input Voltage is defined as the cross-point voltage.

[j] VDD denotes VDDA, VDDB.

Offset from Carrier Frequency (Hz)