Jitter Measurement

Measure waveform total jitter and estimate jitter components

Since R2026a

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  • Jitter Measurement block

Libraries:
Mixed-Signal Blockset / Utilities
SerDes Toolbox / Utilities
Signal Integrity Toolbox / Utilities

Description

Use the Jitter Measurement block to calculate waveform total jitter and other jitter metrics such as deterministic jitter, random jitter, duty cycle distortion, data-dependent jitter, sinusoidal jitter, and inter-symbol interference.

Ports

Input

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Amplitude of the measured waveform, specified as a vector.

Data Types: double

Symbol thresholds for the amplitude of the measured waveform, specified as a vector.

Dependencies

To enable this port, select the Enable symbol threshold input port for Wave parameter.

Data Types: double

Amplitude of the reference waveform, specified as a vector. The block compares this amplitude with the amplitude of the measured waveform.

Dependencies

To enable this port, select the Enable Ref input port parameter.

Data Types: double

Symbol thresholds for the amplitude of the reference waveform, specified as a vector.

Dependencies

To enable this port, select the Enable Ref input port and Enable symbol threshold input port for Ref parameter.

Data Types: double

Use this port to reset the internal states and to restart the averaging of the jitter components.

Dependencies

To enable this port, select the Enable reset port parameter.

Data Types: double

Parameters

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To edit block parameters interactively, use the Property Inspector. From the Simulink® Toolstrip, on the Simulation tab, in the Prepare gallery, select Property Inspector.

Configuration

Select this parameter to enable the input port waveThld. Use the waveThld port to specify the symbol thresholds for the amplitude of the measured waveform.

Programmatic Use

Block parameter: SymbolThresholdPort
Type: character vector
Values: off | on
Default: off

Edge detection thresholds for measured waveform, specified as a real scalar or real-valued row vector.

Dependencies

To enable this parameter, clear Enable symbol threshold input port for Wave parameter in the Configuration tab.

Programmatic Use

Block parameter: SymbolThresholds
Type: character vector
Values: real scalar | real-valued row vector
Default: 0

Symbol time for the measured and reference waveforms in seconds, specified as a positive real scalar.

Programmatic Use

Block parameter: SymbolTime
Type: character vector
Values: positive real scalar
Default: 1e-9

Select this parameter to enable the reference input port, Ref. The Ref port inputs the amplitude of a reference waveform which is compared with the measured waveform.

If you do not input a reference waveform, the block uses an internal reference that supports signals with less than 1 UI peak-to-peak total jitter.

Programmatic Use

Block parameter: ReferencePort
Type: character vector
Values: off | on
Default: off

Select this parameter to enable the input port refThld. Use the refThld port to specify the symbol thresholds for the amplitude of the reference waveform.

Dependencies

To enable this parameter, select Enable Ref input port option in the Configuration tab.

Programmatic Use

Block parameter: ReferenceThresholdPort
Type: character vector
Values: off | on
Default: off

Edge detection thresholds for reference waveform, specified as a real scalar or real-valued row vector.

Dependencies

To enable this parameter, select Enable Ref input port and clear the Enable symbol threshold input port for Ref parameters in the Configuration tab.

Programmatic Use

Block parameter: ReferenceThresholds
Type: character vector
Values: real scalar | real-valued row vector
Default: 0

Select this parameter to enable the reset port. A positive signal at the reset port resets the internal states and restarts the averaging of the jitter components.

Programmatic Use

Block parameter: ResetPort
Type: character vector
Values: off | on
Default: off

Maximum number of sinusoidal jitter frequencies to measure, specified as a positive real scalar.

Programmatic Use

Block parameter: SJFrequencies
Type: character vector
Values: positive real scalar
Default: 1

Length of the recovered impulse response from the measured waveform in UI, specified as a positive real scalar.

Note

If you provide an impulse response using the Impulse response to use for ISI parameter, the block uses the provided impulse response and ignores the value specified in the Length in UI of recovered impulse response parameter.

Programmatic Use

Block parameter: ImpulseResponseLength
Type: character vector
Values: positive real scalar
Default: 256

Correlation method for duty cycle distortion (DCD), specified as one of these:

  • oddeven — The block calculates one timing offset for the edge with odd indices and another timing offset for the edge with even indices. The peak-to-peak DCD is the difference between the two timing offset values.

  • risefall — The block calculates one timing offset for the edge with rising indices and another timing offset for the edge with falling indices. The peak-to-peak DCD is the difference between the two timing offset values.

Programmatic Use

Block parameter: DCDMethod
Type: character vector
Values: oddeven | risefall
Default: oddeven

Bin edges for probability distribution functions (PDFs) during correlation, specified as a vector.

By default, the function distributes bin edges evenly with twice the resolution of Scott's rule.

Dependencies

To enable this parameter, expand the Advanced option in the Configuration tab.

Programmatic Use

Block parameter: BinEdges
Type: character vector
Values: auto
Default: auto

Number of FFT points used by the sinusoidal jitter (SJ) component, specified as a positive integer scalar. If you do not provide the number of FFT points, the block automatically calculates it from the length of the timing error vector.

For best accuracy, the measured SJ frequency should be an integer multiple of the minimum measurable SJ frequency.

Note

If the length of the timing error vector is larger than 214 and you set the number of FFT points it to auto, the block caps it at 214 to reduce processing time. If your design needs it, you can manually set the length of the timing vector to a value larger than 214.

Dependencies

To enable this parameter, expand the Advanced option in the Configuration tab.

Programmatic Use

Block parameter: NFFT
Type: character vector
Values: auto | positive integer scalar
Default: auto

Impulse response to use for ISI, specified as a real-valued row vector. If you do not provide an impulse response, the block automatically recovers an impulse response from the measured waveform.

Dependencies

To enable this parameter, expand the Advanced option in the Configuration tab.

Programmatic Use

Block parameter: ImpulseResponse
Type: character vector
Values: real-valued row vector
Default: []

Symbol levels corresponding to the impulse response used to calculate the ISI, specified as a real-valued row vector. The symbol levels scale the waveform made by convolving the impulse response with the measured symbol pattern to match the symbol thresholds.

Dependencies

To enable this parameter, expand the Advanced option in the Configuration tab.

Programmatic Use

Block parameter: SymbolLevels
Type: character vector
Values: real-valued row vector
Default: []

Duration after a transition that the debouncer is active, specified as a real positive scalar in UI. The block ignores additional threshold crossings when the debouncer is active.

Dependencies

To enable this parameter, expand the Advanced option in the Configuration tab.

Programmatic Use

Block parameter: AntiRingbackDuration
Type: character vector
Values: real-valued row vector
Default: []

Base workspace variable name, specified as a character string. This workspace variable calculates the value of all the metrics for the last collected frame and stores it in the base workspace.

Select this parameter to display the waveform plots after simulation is complete.

Click to display the waveform plots any time after simulation is complete.

Export the jitter metrics to a MAT file.

The block captures the simulation results frame by frame as the simulation progresses. The Symbol decimation parameter determines the length of the frame. The block then uses the results of the last completed frame to calculate the jitter metrics.

Export jitter metrics to a structure in the base workspace.

The block captures the simulation results frame by frame as the simulation progresses. The Symbol decimation parameter determines the length of the frame. The block then uses the results of the last completed frame to calculate the jitter metrics.

Number of UI per data frame, specified as a positive real scalar. The block updates the value once per frame.

The block captures the simulation results frame by frame as the simulation progresses. The Symbol decimation parameter determines the length of the frame. Setting Symbol decimation parameter at a large value increases the accuracy of jitter measurements at the expense of the speed.

Programmatic Use

Block parameter: Decimation
Type: character vector
Values: positive real scalar
Default: 1024

Sample time for the uniformly sampled jittery and reference signal, specified as a positive real scalar or positive real-valued row vector.

Programmatic Use

Block parameter: SampleTime
Type: character vector
Values: positive real scalar | positive real-valued row vector
Default: 1.25e-10

Select the simulation mode. This option affects simulation performance.

Simulating the model using the Code generation method requires additional startup time, but the subsequent simulations run faster. Simulating the model using the Interpreted execution method may reduce the startup time, but the subsequent simulations run slower.

Programmatic Use

Block parameter: SimulateUsing
Type: character vector
Values: Code generation | Interpreted execution
Default: Code generation

Output ports

Select this parameter to enable the TJrms port. The TJrms port outputs the RMS total jitter.

Programmatic Use

Block parameter: TJrms
Type: character vector
Values: off | on
Default: off

Select this parameter to enable the TJpkpk port. The TJpkpk port outputs the peak-to-peak total jitter.

Programmatic Use

Block parameter: TJpkpk
Type: character vector
Values: off | on
Default: off

Select this parameter to enable the RJrms port. The RJrms port outputs the RMS random jitter.

Programmatic Use

Block parameter: RJrms
Type: character vector
Values: off | on
Default: off

Select this parameter to enable the DJrms port. The DJrms port outputs the RMS deterministic jitter.

Programmatic Use

Block parameter: DJrms
Type: character vector
Values: off | on
Default: off

Select this parameter to enable the DJpkpk port. The DJpkpk port outputs the peak-to-peak deterministic jitter.

Programmatic Use

Block parameter: DJpkpk
Type: character vector
Values: off | on
Default: off

Select this parameter to enable the SJa, SJf, and SJp ports. These ports output the amplitudes, frequencies, and phase values of sinusoidal jitter, respectively.

Programmatic Use

Block parameter: SJ
Type: character vector
Values: off | on
Default: off

Select this parameter to enable the DDJrms port. The DDJrms port outputs the RMS data-dependent jitter.

Programmatic Use

Block parameter: DDJrms
Type: character vector
Values: off | on
Default: off

Select this parameter to enable the DDJpkpk port. The DDJpkpk port outputs the peak-to-peak data-dependent jitter.

Programmatic Use

Block parameter: DDJpkpk
Type: character vector
Values: off | on
Default: off

Select this parameter to enable the DCDrms port. The DCDrms port outputs the RMS jitter correlated with duty-cycle distortion.

Programmatic Use

Block parameter: DCDrms
Type: character vector
Values: off | on
Default: off

Select this parameter to enable the DCDpkpk port. The DCDpkpk port outputs the peak-to-peak jitter correlated with duty-cycle distortion.

Programmatic Use

Block parameter: DCDpkpk
Type: character vector
Values: off | on
Default: off

Select this parameter to enable the ISIrms port. The ISIrms port outputs the RMS jitter correlated with inter-symbol interference.

Programmatic Use

Block parameter: ISIrms
Type: character vector
Values: off | on
Default: off

Select this parameter to enable the ISIpkpk port. The ISIpkpk port outputs the peak-to-peak jitter correlated with inter-symbol interference.

Programmatic Use

Block parameter: ISIpkpk
Type: character vector
Values: off | on
Default: off

Click this parameter to select and enable all output ports in the Jitter Measurement block.

Click this parameter to clear and disable all output ports in the Jitter Measurement block.

Version History

Introduced in R2026a

See Also

(Mixed-Signal Blockset) | (Mixed-Signal Blockset) | (Mixed-Signal Blockset) | (Mixed-Signal Blockset) | (Mixed-Signal Blockset) | (Mixed-Signal Blockset) | (Mixed-Signal Blockset) | (Mixed-Signal Blockset) | (Mixed-Signal Blockset) | (Mixed-Signal Blockset) | (Mixed-Signal Blockset)

External Websites