Sampling-Time Jitter

Sampling-Time Jitter

Random variations in the actual sampling instant relative to the ideal sampling instant.

Aperture Jitter

The uncertainty in the exact time at which a sample is taken.

Clock Jitter

Timing fluctuations in the sampling clock that cause sampling instants to vary.

Sampling-Time Error

The difference between the actual sampling instant and the ideal sampling instant (Dt)

Jitter-Induced Amplitude Error

The amplitude error produced when a signal is sampled slightly earlier or later than intended.

Jitter Error Mechanism

Jitter causes larger amplitude errors when the signal is changing rapidly and smaller errors when the signal changes slowly

Signal Slope Dependence

The magnitude of jitter-induced error is proportional to the slope of the input signal.

Worst-Case Jitter Sensitivity

Maximum jitter error occurs at the points where the signal slope is greatest.

Zero-Slope Condition

Jitter produces negligible error when the signal slope is approximately zero

RMS Jitter

The root-mean-square value of timing uncertainty (S_t)

RMS Timing Error

A statistical measure describing the spread of sampling-time variations.

Jitter Noise

Noise generated by random timing variations during sampling

Jitter-Limited Performance

The condition in which system performance is determined primarily by clock jitter rather than quantization noise.

Jitter-Induced Noise Power

The average power associated with sampling errors caused by timing uncertainty

High-Frequency Sensitivity

Higher input frequencies are more sensitive to sampling jitter.

Low-Frequency Sensitivity

Lower-frequency signals are generally less affected by timing jitter.

Jitter Noise Scaling

Jitter noise increases as signal frequency increases

Jitter-Limited SNR

The maximum achievable signal-to-noise ratio imposed by clock jitter

Jitter-Limited SNR Equation

f_in

Symbol in Jitter-Limited SNR Equation that represents input frequency

S_t

Symbol in Jitter-Limited SNR Equation that represents RMS jitter

Frequency Dependence of Jitter SNR

For fixed jitter, increasing input frequency decreases achievable SNR

Clock Quality Requirement

Higher-frequency ADC applications require lower clock jitter

Jitter-Limited Dynamic Range

The maximum dynamic range achievable before timing noise dominates

Equivalent Noise Source

Jitter can be modeled as an additional noise source added to the sampled signal

Deterministic Timing Error

Predictable timing variations caused by periodic disturbances

Random Timing Error

Unpredictable timing variations characterized statistically using RMS values

Sampling Clock

The timing reference that determines when samples are taken

Clock Phase Noise

Frequency-domain representation of timing instability in an oscillator

Phase Noise Relationship

Phase noise in the sampling clock contributes directly to sampling jitter.

Input Frequency Limitation

As input frequency increases, clock jitter increasingly limits ADC performance.

Jitter-Limited ADC Design

ADC design in which clock stability becomes as important as converter resolution.

Higher-Nyquist-Zone Jitter Effect

Signals sampled in higher Nyquist zones are more vulnerable to timing jitter because of their higher frequencies.

Undersampling and Jitter

and

Jitter-Dominated Region

The operating region where further increases in converter resolution provide little improvement because jitter already dominates noise performance

How many

The operating region where converter performance is limited primarily by quantization noise rather than timing uncertainty

Yes, it is true

Very small timing errors can significantly reduce achievable SNR at high frequencies.

Jitter Error Approximation

Equation explains why larger signal slopes create larger jitter-induced errors.