Viewing DC Operating Point Results

In this Topic ShowHide

Schematic Annotation

You can annotate the schematic with the results of a DC operating point analysis. This requires special markers to be placed on the schematic. You can instruct SIMetrix to place markers at every node or you can place them manually.

To place a voltage marker manually use the schematic popup: Bias Annotation ▶ Place Marker or use control-M. The text displaying the value will be placed on the sharp side of the marker which to start with points up. If you are placing the marker on a vertical wire you might wish the text to be on one side. To do this, rotate the marker before placing by pressing the rotate toolbar button or the F5 key.

To place a current marker use the menu Place ▶ Bias Annotation ▶ Place Current Marker.

To place markers as all nodes select Bias Annotation ▶ Auto Place Markers. This does however clutter up the schematic and you may prefer to place them manually.

To display the values select Bias Annotation ▶ Update Values. These values are automatically updated after each simulation run.

The menu Bias Annotation ▶ Delete Markers deletes all the markers and Bias Annotation ▶ Hide Values removes the text but leaves the markers in place.

Displaying Device Operating Point Info

The menu Bias Annotation ▶ Display Device Bias Info will display in the message window the node voltages, pin currents and total power dissipation for the selected schematic part. Note that power dissipation is calculated from the node voltages and currents.

List File Data

A great deal of information about each device in the circuit can be obtained from the list file. Use menu Simulator ▶ Open List File to see it. Also see the Simulator Reference Manual for more information about the list file.

Other Methods of Obtaining Bias Data

You can also display a voltage or current in the command shell without placing any part on the schematic. For voltages, place the mouse cursor over the point of interest and press control-N. For currents, place the cursor over the part pin and press control-I.

Bias Annotation in SIMPLIS

The above apply to operation in both SIMetrix and SIMPLIS modes. When in SIMPLIS mode the dc values displayed represent the results at time=0. For AC analysis this will be the time=0 value for its associated POP analysis.

Bias Annotation Display Precision

By default, bias annotation values are displayed with a precision of 6 digits. To change this, select menu File ▶ Options ▶ General... then edit the value in box Bias Annotation Precision in the Schematic sheet.

Bias Annotation and Long Transient Runs

If you are running a long transient analysis and plan to use bias annotation extensively, you might like to set a simulator option that will make this process more efficient. The simulator option is:

This forces a separate data group and separate data file to be created for the transient analysis bias point data. Unless tstart>0 bias point data is usually taken from t=0 values. The problem with this approach is that to view a single value, the entire vector has to be loaded from the data file to memory. This isn't a problem if the run is only a 100 points or so, but could be a problem if it was 100,000 points. It can take a long time to load that amount of data. By specifying this option, the bias point data is stored separately and only a single value needs to be read from the file. This is much more efficient.