Clock Jitter Measurement

Measure jitter in periodic signals

Since R2021a

• 

Libraries:
Mixed-Signal Blockset / Utilities

Description

Use the Clock Jitter Measurement block to measure the RMS (root mean squared) periodic jitter in clock signals. You can also measure cycle-to-cycle (C2C) jitter and duty cycle distortion (DCD).

Ports

Input

clock — Input clock signal

scalar

Input clock signal, specified as a scalar. The input signal must have only one threshold crossing per period.

Data Types: double

Output

Period Jitter — Running RMS value of period jitter

scalar

Running RMS value of the period jitter calculated up to the current time step, returned as a scalar. Period jitter is the deviation in the cycle time of a clock signal with respect to the ideal period.

Data Types: double

C2C — Running RMS value of cycle-to-cycle jitter

scalar

Running RMS value of the cycle-to-cycle jitter calculated up to the current time step, returned as a scalar. Cycle-to-cycle jitter is the difference in the period between the two consecutive cycles of the clock.

Dependencies

To enable this port, select Cycle-2-Cycle (C2C) Jitter.

Data Types: double

DCD — Difference between real duty cycle and 50% value

scalar

Difference between the real duty cycle in percentage and the ideal 50% value, returned as a scalar.

Dependencies

To enable this port, select Duty Cycle Distortion (DCD).

Data Types: double

Parameters

Clock Frequency — Frequency of input clock signal

1e6 (default) | positive real scalar

Frequency of the input clock signal, specified as a positive real scalar in Hz. Clock Frequency is used to calculate the ideal value of the period of the input signal.

Programmatic Use

Block parameter: Frequency

Type: character vector

Values: positive real scalar

Default: 1e6

Threshold — Threshold signal level

0 (default) | real scalar

Threshold signal level to calculate the rising and falling edge of the signal, specified as a real scalar.

Programmatic Use

Block parameter: Threshold

Type: character vector

Values: real scalar

Default: 0

Period Jitter — RMS period jitter

on (default) | off

Select to calculate the RMS period jitter. This option is selected by default.

Period jitter is the deviation in the cycle time of a clock signal with respect to the ideal period.

Cycle-2-Cycle (C2C) Jitter — RMS cycle-to-cycle jitter

off (default) | on

Select to calculate the RMS cycle-to-cycle (C2C) jitter. This option is deselected by default.

Cycle-to-cycle jitter is the difference in the period between the two consecutive cycles of the clock.

Duty Cycle Distortion (DCD) — Duty cycle distortion for each cycle

off (default) | on

Select to calculate the duty cycle distortion for each cycle. This option is deselected by default.

Duty cycle distortion is the difference between the real duty cycle in percentage and the ideal 50% value.

Simulate using — Select simulation mode

Code generation (default) | Interpreted execution

Select the simulation mode. This choice affects the 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. For more information, see Interpreted Execution vs. Code Generation.

Version History

Introduced in R2021a