Crystal Devices

What Exactly Is Oscillator Jitter? (Part 2)

In this segment, we will define "oscillator jitter," a term that emerges during the evaluation of ICs and the design of circuits.

Jitter Items

There are several methods for measuring jitter, and there are also various jitter parameters.

In this segment, we will delve into the intricacies of representative jitter parameters.

For information on jitter measurement methods, please refer to Part 1.

Typical Measurement Areas and Jitter Items

Jitter items

Period Jitter

This indicates the time deviation of one cycle (period) of the output waveform. When presenting measurement results, the following expression is commonly used.

Peak-to-Peak Jitter	The difference between the maximum and minimum values when statistically processing the time of one cycle at a specified threshold using frequency distribution.
1σ Jitter	The standard deviation (1σ) when statistically processing (frequency distribution) the time of one cycle at a specified threshold.

Cycle-to-Cycle Jitter

The time difference between one period of the output waveform and the time of the adjacent period. When presenting measurement results, the following expression is commonly used.

Peak-to-Peak Jitter	The difference between the maximum and minimum values of the time difference between one cycle and the next cycle when statistically processing (frequency distribution) at a specified threshold.
1σ Jitter	The standard deviation (1σ) when statistically processing (frequency distribution) the difference between the time of one cycle and the next cycle at a specified threshold.

Differences in Results Between Jitter Measuring Instruments

We explained that there are various measurement methods and metrics for jitter, but here we show the results of observing the same device unit and the differences in those numbers.

Article to be measured: CMOS output, clock oscillator, KC7050A125.000C30E00
Measurement environment: ambient temperature, humidity, supply voltage 3.3 V

Measuring Instrument	Domain	Measurement Item (1) and Results		Measurement Item (2) and Results		Measurement Condition
Time Interval Analyzer (TIA)	Time Domain	Period Jitter/ Peak-to-Peak	17.79ps	Period Jitter/ 1σ Jitter	2.25ps	50,000cyc Hits or more
Time Interval Analyzer (TIA)	Time Domain	Cycle-to-Cycle Jitter/ Peak-to-Peak	54.70ps	Cycle-to-Cycle Jitter/ 1σ Jitter	3.51ps	50,000cyc Hits or more
Digital Storage Oscilloscope (DSO)	Time Domain	Period Jitter/ Peak-to-Peak	29.75ps	Period Jitter/ 1σ Jitter	3.13ps	50,000cyc Hits or more
Signal Source Analyzer(SSA)	Freq.Domain	Phase Jitter	0.85ps	--	--	BW:12kHz to 20MHz

While "jitter" is a general term, it varies depending on the measurement parameters and equipment used, so caution is required.
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