Pulsonix Spice Simulation

This is a brief overview of the Pulsonix-Spice Simulation functionality. If you do not have Pulsonix-Spice you can still generate Spice netlists for some Spice formats, specified by using the Set Netlist Spice Type option from the Simulation menu.

The Simulator

When a simulation is run on a schematic design the Pulsonix-Spice SPICE Simulator is activated. The main window of the Simulator is the Pulsonix-Spice Command Shell dialog shown below:

All simulation information about netlists loaded, models used and simulation errors found is reported here.

You can use the Simulator’s menus to:

Add and delete SPICE Model libraries.
Associate Pulsonix-Spice models to Pulsonix parts.
Change the colours and fonts used in graphs.
Create and run simulation scripts.
Plot simulation results using the Add Curve and Fourier options.
Access the Simulator’s Help topics, including simulation error messages.
Access the Simulator’s online manuals.

Use the Simulator’s Help topics to find out more detail about the advanced operation of the Simulator.

Pulsonix Simulation Functionality

Most of the functions to use for Simulation analysis can be found on the Simulation Menu and its many sub menus:

Press F9 to Simulate the Schematic Design and press F7 to edit the selected component’s Spice Values, Parameters or Model Name.

All of the options on this menu, and its sub menus have links listed in the Simulation Topics at the bottom of this page.

Some of the more commonly used functions have been added to a Simulation Toolbar:

Preparing the Schematic for Simulation

In short, the method for using Pulsonix Spice is to use information on parts to indicate what SPICE device they represent, the SPICE model to use during the simulation, and how to output them to a SPICE netlist.

These parts can represent circuit stimuli (like voltage and current sources), basic SPICE devices (analog and digital), sub-circuits, special Pulsonix-Spice functional models and Simulator commands (like Probes and Initial Conditions).

You can set up a part SPICE type and Pulsonix-Spice information by editing it using the library manager and using the Edit Spice button from the Details page. This presents the Define Spice Type dialog to specify the type of device the part represents.

Libraries are provided for use within Pulsonix containing parts that have Spice information already set up to help you quickly generate circuits to simulate. These libraries can also be used as a guideline to be referenced when creating your own libraries. These parts can be found in the Spice parts library, and its corresponding symbol library. It contains special parts for functional modelling, circuit stimuli, probes etc., along with hundreds of parts that reference the Pulsonix-Spice simulator models and subcircuits.

Add the required parts from these libraries to your schematic using one of the following methods:

Add your circuit stimuli components using the Insert Source sub menu on the Simulation menu. The menu will contain a list of commonly used source devices.
Add your circuit probe components using the Insert Fixed Probe sub menu on the Simulation menu. The menu will contain a list of probe parts representing commonly used simulation plots. The menu also contains a set of simulator control parts, Keep parts for controlling what values to store during a simulation, and Watch parts to perform simple Safe Operating Area (SOA) limit tests.
For the more commonly used Spice parts, use the quick access Parts Toolbar to select parts the pop-up buttons, each of which displays a toolbar representing parts from a particular category.
For a structured tree based access to all of the parts from the Spice library, use the Spice Category within the Part Browser.
If you know the name of the Spice model, use the Insert Part Using Model option from the Simulation menu.
Lastly, use the normal Insert Component dialog to access the parts libraries.

Once added, you can alter the Spice information on the components in your circuit by selecting them and pressing F7, or using the Edit Spice Model/Value command from the Simulation menu. For most devices this will bring up the Select Model dialog to change the model or subcircuit the component refers to and its model parameters, or the Define Passive Device dialog to change the value of resistors, capacitors, inductors etc. There are many more special dialogs that respond to the F7 key for different Spice device types, these are listed below.

Connect up to these components to create the circuit to be simulated. Insert circuit stimuli by adding voltage and/or current source parts to the circuit. Add fixed voltage and current probe components to the nets and pins that you wish to plot a simulation curve.

The following design rules must be observed for the simulation to run correctly. Note that most circuits obey them anyway and they do not impose serious limitations on the capability of the simulator.

There must always be at least one ground symbol on every circuit.
Every node on the circuit must have a dc path to ground. If you do have a floating node, connect a high value resistor (e.g. 1G ) between it and ground.
There must not be any zero resistance loops constructed from voltage sources and or inductors. If you do have such loops. insert a low value resistor. It is best to make the resistance as low as is needed to have a negligible effect on your circuit but no lower.
There should be at least two connections at every node.

Failure to observe the above usually leads to a “Singular Matrix” error.

When the circuit is ready, use the Simulation Parameters option from the Simulation menu to choose the analysis mode.

Running Simulations

Starting the Simulation

When all set up, run the Simulate Design option from the Simulation menu. All pages of the schematic will be collated and the entire schematic simulated. To simulate only parts of a schematic design, use the Simulate Current Page and Simulate Selected Items options available from the Simulation Toolbar. The simulator will be run in synchronous mode, so you cannot use any part of the program while the simulation is running.

A SPICE netlist will be generated and sent to the Pulsonix-Spice simulator for analysis. If the simulator is not already running it will be launched at this point which may take a few seconds. The “Pulsonix-Spice Command Shell” window will appear which will report any errors found interpreting the SPICE netlist.

If the design contains fixed probe components, their curves will be plotted in a simulator graph window. Alternatively you can use the interactive Random Probe facility from the schematic editor Simulation menu, or you can use the Add Curve option in the simulator itself to plot results.

Netlist Contents

The netlist contains the following:

A SPICE description of the circuit

This is a netlist extracted from the schematic design.
Analysis Mode and Simulation control commands

These are instructions to the simulator to tell it how to perform the simulation of the circuit. They are set up using the Simulation Parameters dialog, described in more detail below. The parameters are held in the schematic design.
Extra SPICE data

This is any other information that you wish to include in the netlist. The text is set up using the Extra Simulation Data dialog, and is also held in the design.

It is usually used to contain more advanced simulation commands that cannot be set up using the dialogs provided in the Pulsonix program, or to include descriptions of models used in the circuit that either do not exist in the model libraries or have been changed.

Once the netlist has been successfully read the simulation of the circuit will be performed. A “Simulator Running” dialog will open showing the status of the simulation.

Pausing and Aborting Analyses

You can pause the simulation by selecting the Pause button on the simulator status dialog. To restart select the Resume button (the Pause button changes name when simulation pauses) or the simulator Resume menu item. There is no obligation to resume a simulation that has been paused. If you start a new run after having paused the previous one, you will be asked whether you wish to abandon the pending simulation run.

There is actually never a need to explicitly abort an analysis. If you decide you do not wish to continue a run, just pause it as described above. Pause is the same as abort except that you have the option to change your mind and restart. Nevertheless there is an abort facility. Simply select the simulator Abort menu item. When you abort a run, you will not be able to restart it. There is just one benefit of aborting a run instead of pausing it. When an analysis is aborted, the simulator frees up the memory it needed for the run. Note that this does not happen after a run completes normally. If you need to free up simulator memory after a normal run completes, type “Reset” at the Pulsonix-Spice command window.

Abort, Pause and Resume are also available from the simulator sub menu on the schematic simulation menu.

Running Analyses in Asynchronous Mode

In asynchronous mode, the simulation runs in the background and you are free to carry on using the Pulsonix environment for entering schematics or viewing results from previous analyses. Because, the simulation is running in the background, it is necessary for the simulation process to be detached from the front end environment and for this reason it is not possible to use .GRAPH or fixed probes to plot simulation results during the course of the run. Also you must manually load the simulation data when the run is complete.

To start an asynchronous run.

Select option Run Asynchronous from the schematics simulation menu. A simulation status box appears similar to the box used for synchronous runs but with an additional Activity box at the bottom. Any messages generated by the simulator will be displayed here.
When the simulation is complete, you must load the data manually. The name of the file to load will be displayed in the command shell when the simulation starts. In the simulator, select menu “File/Data/Load Temporary Data” to load the data file. You will be able to random probe the schematic used to run the analysis in the normal manner once this file is loaded.

To pause Asynchronous Runs, press the Pause button. Note that you can load the data generated so far after pausing the run as described above. To abort a run, press the Close button.

Restarting a Transient Run

After a transient analysis has run to completion, i.e. when it has reached its stop time, it is still possible to restart the analysis to carry on from where it previously stopped. To restart a transient run select the Restart Transient option from the schematics simulation menu. The following dialog will be displayed by the simulator:

In the New Stop Time box enter the time at which you wish the restarted analysis to stop. Press OK to start the run.

Annotation of Simulation Results

After the simulation has been completed, you can use Bias Annotation to annotate the Schematic with the results of the DC operating point analysis. This requires special markers to be placed on the Schematic. You can instruct Pulsonix to place markers at every node or you can place them manually. The options to perform this can be found on the Bias Annotation sub menu from the Simulation menu.

The format of the bias markers in the schematics can be changed using the Simulation Parameters dialog. Change to the Options page and use the Bias Annotation Format section to set the required format type and precision. Simulate again to see results change.