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SIMetrix provides two methods of creating plots of simulated results.
The first approach is to fix voltage or current probes to the schematic before or during a run. SIMetrix will then generate graphs of the selected voltages and/or currents automatically. The probes have a wide range of options which allow you to specify - for example - how the graphs are organised and when and how often they are updated.
The second approach is to randomly probe the circuit after the run is complete. (You can also do this during a run by pausing first). With this approach, the graph will be created as you point the probe but will not be updated on a new run.
You do not need to make any decisions on how you wish to probe your circuit before starting the run. You can enter a circuit without any fixed probes, run it, then randomly probe afterwards. Alternatively, you can place - say - a single fixed probe on an obvious point of interest, then randomly probe to investigate the detailed behaviour of your circuit.
Fixed schematic probes are limited to single ended voltages and currents and differential voltages. The random probing method allows you to plot anything you like including device power, FFTs, arbitrary expressions of simulation results and X-Y plots such as Nyquist diagrams. It is possible to set up fixed probes to plot arbitrary expressions of signals but this requires manually entering the underlying simulator command, the .GRAPH control. There is no direct schematic support for this. For details of the .GRAPH control see the "Command Reference" chapter of the Simulator Reference Manual.
There are several types of fixed probe. Three of the commonly used probes are:
There are more fixed probes available in addition to those described above. See Fixed Probes for details.
You can place these on a schematic with the single hot key 'B' or with one of the menus:
If you place the probe immediately on an existing schematic wire, SIMetrix will try and deduce a meaningful name related to what it is connected to. If you place the probe at an empty location, its name will be a default (e.g. PROBE1-NODE) which won't be meaningful and you will probably wish to subsequently edit it.
You can place these on a schematic with the single hot key 'U' or with one of the menus schematic popup
Current probes must be placed directly over a part pin. They will have no function if they are not and a warning message will be displayed.
These can be placed using one of the menus
Most of the entries in the schematic's Probe menu are for random probing. You can probe, voltage, current, differential voltage, device power, dB, phase, Nyquist diagrams and much more. You can also plot arbitrary expressions of any circuit signal and plot signals from earlier simulation runs. Just a few of the possibilities to get you started are explained below. For a full reference see Random Probes.
In AC analysis you will probably want to plot signals in dB and you may also want to plot the phase of a signal.
The schematic menu allows you to plot the voltage difference between two points. When you select this menu click on the schematic twice. The first is the signal node and the second the reference node.
The menu provides many more probing functions selectable from a tree structured list. More advanced plotting can be achieved with the menu . This opens a dialog box allowing you to enter any expression and which also provides a range of options on how you wish the graph to be plotted.
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