Transient and Fourier Analysis Setup

A "Transient" analysis generates a voltage/current against time waveform plot.

Set the start, stop and maximum calculation step times that data is desired to be plotted over. A good default for the maximum calculation step size is equal to 1/100 of the total print time. If better resolution is required in the graph, or the graph looks too jagged it can be set to a smaller value. It may also be necessary, on occasions to set a smaller step size in order to get convergence. If it is set too small, the simulation will take much longer and the data file will get very large.

Marching Waveforms

Transient waveforms can be continuously plotted as the simulation progresses, this is referred to as marching waveforms. To enable this feature check the "Enable Marching Waveforms check box. There is a small reduction in simulation speed with this option, in addition multiple runs such as parameter sweep and worst case re-run analysis are not supported with marching waveforms enabled and will therefore be automatically disabled. Marching of other waveform types are also not supported. In addition, only operating point, ac and dc analysis can be ran in conjunction with a marching transient waveform. All others will be automatically disabled.

Note that the simulation can be paused and continued via the run menu or the relevant toolbar button.

Existing installs may not show the pause button in the "SS SO PO G.." group or the enable marching windows button in the "op dc ac ns tr ..." group. Press the small black modify toolbar button on the respective toolbar to add these buttons.

Full Scale Marching X Axis

This option keeps the x - axis at the full range of the simulation stop points. Clearing this check will allow the simulation to auto scale the graph x axis as the simulation progress. The Y - axis is always auto scaled if the graph has not been manually zoomed.

Marching Waveform Issues

Very short transient runs can result in data read errors. This is due to communication synchronization issues between the SuperSpice GUI and the XSpice simulation engine. The solution is to disable marching waveforms, which would be pointless anyway, for such short runs.

UIC

If a run requires to use the initial conditions specified on capacitors and inductors the "use initial conditions" box must be checked

Frequency Calculator

The frequency calculator section allows the average fundamental frequency of a waveform to be calculated automatically. The frequency determining search is from a start cycle count to an end cycle count at equal Y values.

Enable - Enables the frequency calculation feature.

Positive/Negative edge select.

Cycle counts - determines the start and stop ranch with with to calculate the average frequency. Typically, the first few cycles of an oscillator is not at its final value. Ignoring the first few cycles will therefore give a more accurate value to the final frequency.

Xcrossing value - Sets the voltage or current to be used as a reference point for extracting equivalent points at each cycle. Typically this should be at the value midway between the maximum and minimum value of the waveform.

Data from all runs can be obtained by using the "View" menu, and selecting the "Analysis Results\Transient Frequency" menu item. New results with different setup data can be obtained without running the simulation again.

FFT

Linearize Transient Data

The check must be enabled for FFT data. By default, the transient run data step size is variable. FFT's require a constant time step. This check enables a routine that post processors the raw simulation data and converts it to a linear format.

Auto Calculate FFT

This options instructs SuperSpice to automatically calculate the FTT of waveforms after a run has been performed and display the FFT graph.

Calculate FFT for Test Points only

Only signals attached to test points will have FFT data calculated. This is to avoid needless time processing signals not required.

Interactive Real Time Simulations

The values of resistors, capacitors, inductors, and voltage and current sources can be changed in real time as the simulation progress. To enable this feature, check the "Enable real time changes" check box in the Transient set-up. This allows any changes to these components to be sent to the engine whilst the simulation is progressing. "Marching Waveforms" have to be enabled for interactive real-time simulations.

Simulation Speed

For real-time changes it may be advantages to slow the simulation speed. The initial value of simulation delay can be set by enabling the "Spice Options" tab set-up, "Simulation Wait Time". This value is in milliseconds. This can be changed as the simulation progress via the "XSpice Progress Rate", or "xR" setup dialog. The wait time is the time between simulation update time set by the "Transient Progress Rate" count, noting that a transient progress rate count of 100 means that update data will be sent in 1% increments of the total run time.

Notes: Changing components instantaneously may give strange results at the switch point.

Simulation Setup

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