Stimulus Dialog

The Stimulus dialog allows you to configure digital stimuli, and add or delete user stimulus files. It is displayed by selecting a signal in the Signals tab in Constraint Browser, and then clicking in the Stimulus column in the Analysis tab. It is also displayed in Electrical Editor by selecting an appropriate symbol on the canvas and clicking Edit > Set stimulus on the main menu or clicking Set stimulus on the assist menu.

Stimulus Filename

Allows you to add and delete stimulus files, and view the stimulus files that you select in the Stimulus Filename list.

Item	Description
Stimulus Filename box	Allows you to create a stimulus file. Define the name of the stimulus file and click Add. The file is added to the Stimulus Filename list. The name must be unique, and must not contain spaces.
Add	Moves the name that you define in the Stimulus Filename box to the Stimulus Filename list.
Stimulus Filename list	Displays the available stimulus files.
Save	Saves the details that you specify for the stimulus file that you select in the Stimulus Filename list.
Delete	Deletes the stimulus file that you select in the Stimulus Filename list.

Bit pattern

This section allows you to configure each Bit pattern. The Bit pattern box displays the timing of the stimulus against the predefined clock signal. The time scale is also shown. The Bit pattern display is updated automatically according the settings that you specify. The following types of digital stimulus can be configured.

Value	Description
Pseudo random	Defines a stimulus using pseudo random numbers that are based on a specified number of bits. This option allows you to create a longer bit pattern that can be used for eye diagram simulations, for example.
8b/10b encoding	Allows you to define a stimulus that maps 8-bit words to 10-bit patterns. This is a standard method that is used for PCI Express and other technologies. A bit pattern sequence is created with the regular number of 1s and 0s, which eliminates the DC level from the system. This also eliminates a bit sequence where 1s and 0s are aligned alternately. This maintains a relatively low channel bandwidth.
Constant High	Allows you to define a stimulus using a constant high voltage. This is useful for coupled simulations where one or more passive signals are the target of crosstalk analysis.
Constant Low	Allows you to define a stimulus using a constant low voltage. This is useful for coupled simulations where one or more passive signals are the target of crosstalk analysis.
Periodic Pulses	Allows you to define a periodic stimulus. The defined pattern repeats until the specified simulation time is reached.
Custom Pulses	Allows you to define an arbitrary bit sequence, and adjust it to match the specified clock signal.

 

 

Pseudo random

Item		Description
Bit pattern display		Provides a graphical representation of the selected bit pattern.
Bit Order		Specify a bit order between 1 and 15. The other fields in this group are updated automatically.
Encoding	None	No encoding is used.
	8-10 Bit	Provides error correction. This encoding is specific to some types of bus.
Length of Sequence		The length of the sequence associated with the value specified in the Bit Order field. This is set automatically when you specify a value in the Bit Order box.
Current Bit		The length of the value that you enter in the Enable box.
Data		Represents the data signal as a binary value.
	Edge	Allows you to set the synchronization for the data signal.
		single: synchronization occurs only at the rising edges of the clock signal.
		both: synchronization occurs at the rising and falling edges of the clock signal.
Enable		Set values for the enable signal using the numbers 1 and 0. The length of the value that you enter is displayed in the Current Bit box.
	Edge	Allows you to set the synchronization for the enable signal.
		single: synchronization occurs only at the rising edges of the clock signal.
		both: synchronization occurs at the rising and falling edges of the clock signal.

8b/10b encoding

Item		Description
Character Word		Select a conversion code for extracting a 10-bit pattern.
Length of Sequence		The length of the stimulus sequence.
Current Bit		The length of the value that you enter in the Enable box.
Data		Represents the data signal as a binary value.
	Edge	Allows you to set the synchronization for the data signal.
		single: synchronization occurs only at the rising edges of the clock signal.
		both: synchronization occurs at the rising and falling edges of the clock signal.
Enable		Set values for the enable signal using the numbers 1 and 0. The length of the value entered in the field is displayed in the Current Bit box.
	Edge	Allows you to set the synchronization for the data signal.
		single: synchronization occurs at the rising edges.
		both: synchronization occurs at the rising and falling edges of the clock signal.

Constant High/Constant Low

Item		Description
Length of Sequence		The length of the stimulus sequence.
Current Bit		The number of bits that are entered in the Enable box.
Data		Represents the data signal as a binary value.
	Edge	Allows you to set the synchronization for the data signal.
		single: synchronization occurs only at the rising edges of the clock signal.
		both: synchronization occurs at the rising and falling edges of the clock signal.
Enable		Set values for the enable signal using the numbers 1 and 0.
	Edge	Allows you to set the synchronization for the data signal.
		single: synchronization occurs at the rising edges.
		both: synchronization occurs at the rising and falling edges of the clock signal.

Periodic Pulses

Item		Description
Length of Sequence		The length of the stimulus sequence.
Current Bit		The number of bits that are entered in either the Enable box or the Data box, that is selected.
Data		Represents the data signal as a binary value.
	Edge	Allows you to set the synchronization for the data signal.
		single: synchronization occurs only at the rising edges of the clock signal.
		both: synchronization occurs at the rising and falling edges of the clock signal.
Enable		Set values for the enable signal using the numbers 1 and 0.
	Edge	Allows you to set the synchronization for the data signal.
		single: synchronization occurs at the rising edges.
		both: synchronization occurs at the rising and falling edges of the clock signal.

Custom Pulses

Item		Description
Length of Sequence		The length of the stimulus sequence.
Current Bit		The length of the value that you enter in the Enable box.
Data		Represents the data signal as a binary value.
	Edge	Allows you to set the synchronization for the data signal.
		single: synchronization occurs only at the rising edges of the clock signal.
		both: synchronization occurs at the rising and falling edges of the clock signal.
Enable		Set values for the enable signal using the numbers 1 and 0.
	Edge	Allows you to set the synchronization for the data signal.
		single: synchronization occurs at the rising edges.
		both: synchronization occurs at the rising and falling edges of the clock signal.

Clock

Set the frequency, duty cycle and initial delay for a selected bit pattern. These values cannot be set for Constant High or Constant Low bit patterns.

Item	Description
Frequency	Set the frequency of the stimulus.
Duty Cycle	Set the duration of the high level in the signal cycle of the stimulus.
Initial Delay	Set the initial delay of the stimulus.

Jitter Generation

Jitter is defined as deviation from ideal clock timing. The actual jitter value is generated randomly for each bit.

Item		Description
Jitter Generation		If selected, then Jitter Generation fields are made available and jitter values can be specified.
Amount		Sets the amount of jitter as a percentage of the unit length of the data signal. The ideal start time of a bit, relative to the clock, fluctuates within the specified range.
Type	Gaussian	Distributes the jitter according to the Gaussian distribution function. The jitter that is set in Amount is five times larger than the standard deviation for Gauss distribution.
	Uniform	Distributes the jitter in a regular way within the specified range.
Refresh		Generates random jitter.

Data

Set a value for each Data item, if required. Initial Level cannot be set for Constant High or Constant Low bit patterns.

Item		Description
Initial Level	Inverted first bit	Sets the initial level of the stimulus to the inverted value of the first bit.
	Same as first bit	Sets the initial level of the stimulus to the value of the first bit.
	Low	Sets the initial level of the stimulus to the low level.
	High	Sets the initial level of the stimulus to the high level.
Customize		Changes the bit pattern to Custom pulses. This enables you to edit data values.
Invert		Inverts the current value of all bits.

Simulation Options

Item	Description
Simulation Time	Set the length of time for simulation. Select the relevant units in the accompanying list. The following units can be selected. ms us ns ps