Analyses Setup

Parent Page: SIM Dialogs

The General Setup tab of Analyses Setup Dialog.

Summary

The various analyses that can be performed by the Mixed Simulator are defined in the Analyses Setup dialog. This dialog, through its General Setup page, also allows you to specify the scope of the simulation and the signals to be automatically displayed upon completion of the simulation.

Access

Run command Design » Simulate » Mixed Sim to access this dialog.

Options/Controls

Each individual analysis type is configured on a separate page of the dialog. Simply click on the analysis name to activate the corresponding setup page. The following basic analysis types are supported, click a link to learn more about that analysis type:

• Operating Point Analysis
• Transient Analysis
• Fourier Analysis
• DC Sweep Analysis
• AC Small Signal Analysis
• Impedance Plot Analysis
• Noise Analysis
• Pole-Zero Analysis
• Transfer Function Analysis
• Monte Carlo Analysis
• Parameter Sweep
• Temperature Sweep

The Advanced Options page of the dialog enables you to define advanced simulation options, including the values of SPICE variables, the integration method used by the Simulation Engine and the simulation reference net. In general, you should not have to change any of the parameters in this page of the dialog for accurate simulation. Only change these options if you understand SPICE simulation parameters. To learn more about the Advanced SPICE options, refer to the Advanced SPICE Options article.

The generated SPICE netlist incorporates analysis setup information. This information is initially sought in the project file. If the design is being simulated for the first time and you have not run the Analyses Setup dialog, then default analysis information will be used (Transient and Operating Point analyses). After this initial simulation, and whenever you change the setup information in the Analyses Setup dialog, the project will appear as being modified. Saving the project will result in the information being stored in the project file. Subsequent simulation of the design will generate the netlist using this stored information.

Running a simulation from the schematic will use the schematic-generated SPICE netlist, regardless of whether another SPICE netlist file is open in the main design window. The netlist will be regenerated each time a simulation is run. Any warnings or errors - either with respect to generation of the SPICE netlist, or the actual simulation process itself - will be displayed in the Messages panel.

A simulation can be run directly from an open SPICE netlist, regardless of whether it is part of the project or a free document. The .nsx file can be edited manually, prior to running a simulation from it, but care should be taken and indeed you should have good knowledge of SPICE in order to proceed down this path. If you do make modifications to the netlist and then close it, you should save it under a different name, otherwise running a simulation from the schematic will result in the modified file being overwritten when the SPICE netlist is regenerated from the schematic. Again, any warnings or errors - with respect to the actual simulation process itself - will be displayed in the Messages panel.

As the simulation proceeds and the defined and enabled analyses are performed, a simulation waveform file (*.sdf) will open as a separate tab in the main design window, to display the results of the analyses in the Sim Data Editor's Waveform Analysis window.

General Setup

General setup options for running a circuit simulation are defined on the General Setup page of the Analyses Setup dialog. This is the default page whenever the dialog is launched. To get back to this page from the setup page of another analysis type, simply click the General Setup entry in the Analyses/Options list.

Collect Data For - Specifying the Simulation data to be Collected

Because an enormous amount of data can be collected during a simulation, this option is used to specify which points on the circuit and what type of data you wish to save as simulation results. It is recommended to enable the least amount of data needed, to ensure the shortest possible simulation time. The following options are available:

• Node Voltage and Supply Current - saves data for the voltage at each node and the current in each supply.
• Node Voltage, Supply and Device Current - saves data for the voltage at each node and the current in each supply and each device.
• Node Voltage, Supply Current, Device Current and Power - saves data for the voltage at each node, the current in each supply and the current and power in each device.
• Node Voltage, Supply Current and Subcircuit VARs - saves data for the voltage at each node, the current sourced from each supply and the voltages/currents calculated in subcircuit variables.
• Active Signals - saves results ONLY for signals shown in the Active Signals list. Use this option when you want to minimize the size of the result file. Signals are restricted to node voltages and supply currents.

Sheets to Netlist

Use this field to specify which schematic sheets should be included in the SPICE netlist that is passed to the Simulator. You can choose to run a simulation on the active schematic sheet or the entire set of source schematics in the active project.

SimView Setup

Use this field to specify the simulation view, Keep last setup or Show active signals.

Available Signals

When setting up a simulation you can choose which variables are automatically displayed in the Sim Data Editor's Waveform Analysis window, after the analyses have been done. The Available Signals region of the page shows a list of all available circuit signals that can be plotted. Which signals are available is determined by the type of data that is being collected and saved in the result document, set in the Collect Data For field. 

To have a signal automatically plotted in the Waveform Analysis window, select the signal in the Available Signals list and click the > button to move the signal into the Active Signals list.

The following is a list of the different signal types that can appear in the Available Signals list:

Active Signals

This region lists out all signals for which waveforms will be shown in the Sim Data Editor's Waveform Analysis window after simulation.

Notes

1. Double-clicking on a signal moves it from one list to the other. You can select multiple signals in a list by clicking-and-dragging the mouse over the signal list, or using the Shift and Ctrl keys while clicking on signals. 
2. While including a signal in the Active Signals list causes the simulation results for that signal to be automatically displayed in the Waveform Analysis window, once the simulation has finished, you can use the controls in the Sim Data Editor to display any signal for which data was collected.
3. By default, the Simulator uses the Waveform Analysis window setup information from the previous simulation run to display the simulation results. If you change the Active Signals list from a previous simulation run, you must set the SimView Setup option to Show active signals for any changes to the displayed waveforms to take effect. When this option is on, the Waveform Analysis window is reset to its default condition and the plot waveforms are read from the dialog list, rather than from the previous simulation run.