Aperture Jitter Measurement

R2026b

Measure aperture jitter of periodic signals

• 

Aperture Jitter Measurement block

To add a block to a model, double-click the canvas and start typing the block name. Then, select the block from the list.

Libraries:
Mixed-Signal Blockset / ADC / Measurements & Testbenches

Description

The Aperture Jitter Measurement measure the aperture jitter of periodic signals. In practical data converters, there is a delay between the sampling edge of the sample clock signal and when the sample is actually taken. This delay is known as aperture delay. Aperture jitter is the sample to sample variation between aperture delay.

Ports

Input

clk — Clock signal input

scalar

Clock signal input, specified as a scalar in volts.

Data Types: double

Output

jitter — Jitter output

scalar

Aperture jitter output, returned as a scalar in seconds.

Data Types: double

Parameters

Jitter Metric — Select jitter metric to measure

RMS Aperture Jitter (default) | RMS Period Jitter

Select the jitter metric you want to measure, specified as RMS Aperture Jitter or RMS Period Jitter.

Programmatic Use

Block parameter: JitterMetrick

Type: character vector

Values: RMS Aperture Jitter | RMS Period Jitter

Default: RMS Aperture Jitter

Use external reference signal — Option to use external reference signal

off (default) | on

Select this parameter to enable the use external reference signal against which to measure aperture jitter. By default, this option is cleared.

Dependencies

To enable this parameter, set Jitter Metric to RMS Aperture Jitter.

Programmatic Use

Block parameter: ExternalReference

Type: character vector

Values: off | on

Default: off

Min (V) — Minimum value of clock signal

0 (default) | real scalar

Minimum value of clock signal, specified as a real scalar in volts.

Dependencies

To enable this parameter, set the Jitter Metric parameter to RMS Aperture Jitter and select the Use external reference signal parameter.

Programmatic Use

Block parameter: InputMin

Type: character vector

Values: real scalar

Default: 0

Max (V) — Maximum value of clock signal

1 (default) | real scalar

Maximum value of clock signal, specified as a real scalar in volts.

Dependencies

To enable this parameter, set the Jitter Metric parameter to RMS Aperture Jitter and select the Use external reference signal parameter.

Programmatic Use

Block parameter: InputMax

Type: character vector

Values: real scalar

Default: 1

Frequency (Hz) — Average frequency of input clock

1e6 (default) | real positive scalar

Average frequency of the input clock signal, specified as a real positive scalar in Hz.

Dependencies

To enable this parameter:

• Either set the Jitter Metric parameter to RMS Aperture Jitter and clear the Use external reference signal parameter.

• Or set the Jitter Metric parameter to RMS Period Jitter.

Programmatic Use

Block parameter: Frequency

Type: character vector

Values: real positive scalar

Default: 1e6

Phase (s) — Phase of input clock signal

0 (default) | real scalar

Phase of the input clock signal, specified as a real scalar in seconds.

Dependencies

To enable this parameter, set the Jitter Metric parameter to RMS Aperture Jitter and clear the Use external reference signal parameter.

Programmatic Use

Block parameter: Phase

Type: character vector

Values: real scalar

Default: 0

Specify window length — Option to specify window length

off (default) | on

Select this parameter to specify the window length of the moving average to compensate for the effects of a static frequency offset. By default, this option is cleared.

Dependencies

To enable this parameter, set Jitter Metric to RMS Aperture Jitter.

Programmatic Use

Block parameter: SpecifyWindowLength

Type: character vector

Values: off | on

Default: off

Window length — Window length of moving average

1000 (default) | positive real integer

Window length of the moving average to compensate for the effects of a static frequency offset, specified as a positive real integer.

Dependencies

To enable this parameter, set the Jitter Metric parameter to RMS Aperture Jitter and select the Specify window length parameter.

Programmatic Use

Block parameter: WindowLength

Type: character vector

Values: positive real integer

Default: 1000

Hold off time (s) — Delay before measurement analysis

0 (default) | nonnegative real scalar

Delays measurement analysis to avoid corruption by transients, specified as a nonnegative real scalar in seconds.

Programmatic Use

Block parameter: HoldOffTime

Type: character vector

Values: nonnegative real scalar

Default: 0

Recommended min simulation stop time (s) — Minimum time the simulation must run for meaningful result

Read-only: 1.200e-2 (default) | scalar

This parameter is read-only.

Minimum time the simulation must run for meaningful result, returned as a scalar in seconds. This is calculated using the JEDEC Standards for measuring aperture jitter.

Programmatic Use: Add Block

To add the block programmatically, use the add_block function with one of these library block paths as the source.

"msbAdcMeasurements/Aperture Jitter Measurement"

Example: add_block("msbAdcMeasurements/Aperture Jitter Measurement","myModel/myBlock",MakeNameUnique="on")

For information about programmatic access to individual block parameters, see the Programmatic Use section of parameter descriptions on this page.

Version History

Introduced in R2019a

R2026a: Measuring Jitter When Measured Signal Mismatches with Reference Signal

The Aperture Jitter Measurement block now uses an updated algorithm to better cover cases where the reference signal is not a perfect frequency or good phase match for the measured signal.