OrCAD PSpice 9.2 Tutorial

We will use Orcad schematic capture program and PSPice to simulate the circuits.

Getting started

  1. Start the Orcad schematic capture program (Start -> Programs -> Orcad Family Release 9.2 Lite Edition -> Capture Lite Edition)
     
  2. Start a new project (or open an existing one) (File -> New -> Project...)
     
  3. In the dialog that opens, provide a project name, a file path to where you want your project stored, and select the item "Analog or Mixed-Circuit Wizard". Click OK.

     
     

Placing parts, editing parts, and wiring the circuit

  1. Create the schematic by picking a DC voltage source. Select "Part" from the "Place" menu (or click on the second item in the vertical toolbar) to open a dialog that allows you to choose the part you want to use. For first time user, you need to add library by clicking on Add Library. After that, you need to choose the library from the lower list and then pick the particular library part from the upper list. From the library list, choose SOURCE and then from parts list choose VDC. You should see a DC voltage source symbol appear in the pane at the bottom. Click OK.

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  2. Placing the voltage source
    You will be returned to the drawing window. The symbol of a DC voltage source will be attached to the cursor. Drag it to point in drawing window and click the left mouse to place it. A voltage source symbol will remain attached to the cursor (in case you wanted to place more voltage sources). To get rid of it, click the right mouse button and choose "End mode" from the pop up menu. If you don't like where you've located the source, you can select it and move it to a new spot.



     
  3. Place other components
    Now add transistor and other parts using the same method to pick and place the parts. Transistor are in the Breakout library. Note that there are a number of transistor choices in the library. Choose the correct one for this design.



     
  4. Wire the parts together and add the ground connection
    Use the wire tool to connect the parts. Select the "Wire" item from the "Place" menu (or click on the third item in the vertical toolbar) to activate the wire tool. To wire the nodes together, click on an end of one part, drag the mouse to the end of another part and click again.

    Every SPICE circuit needs a ground connection. To add a ground, use the menu (Place -> ground). A dialog opens. Choose the symbol 0 from the library SOURCE. Place the ground in the desired place and then use the wire tool to connect it into the circuit.



     
  5. Device model
    Some devices (semiconductor devices in particular) that are included in SPICE require many parameter values. Often, many devices in a circuit are defined by the same set of device model parameters. For these reasons, a set of device model parameters is defined on a separate .MODEL line and assigned a unique model name in the PSpice Model Editor Lite.

    To set the parameter of the device, select the device and go to Edit->Pspice model. Click it to open PSpice Model Editor Lite.

    Copy the parameter from SPICE Model Link. Save the file before you close the program.



     

  6. Changing parameters

    When the components were placed, the names and values were set to defaults. Generally, we need to use other component values and would like the option of picking our own names. The schematic capture program provides two methods for changing the properties of components. The name or value can be changed by double-clicking directly on either the name or the value and typing in the new value in the dialog that appears. Note that you can also move the name and value labels around on the schematic in order to make things easier to read.
    The other way to change names and parameters is to double-click on the part symbol directly (or select it with a single click and choose "Properties..." from the "Edit" menu or click once to select it and then right-click to bring up a pop-up menu from which you can choose "Edit Properties...".) A dialog will appear that has all of the properties (names and parameters) for the part. These can be edited in the dialog.  Don not forget to set transistors' length and width.



     
  7. Setting up the analysis
    Now that the circuit is completed, you are ready to tell PSPICE how to analyze the circuit. From the "PSPICE" menu, select the menu item "New Simulation Profile". A small dialog appears that asks you to give a name to the simulation profile you are creating. Choose something like "Transient Analysis" and click on "Create". Another dialog with many tabs appears. The only tab that is important at this point is the one labeled "Analysis". In this case, we want to do a transient analysis of the circuit, so we want to choose "Time Domain (Transient)" in the pop-up menu. In an Transient analysis, PSPICE will run certain time as user specified. For this example, set the Running Time to 20ns and Start time to 0. When finished entering all the information for the Transient Analysis, click OK (or Apply)



     
  8. Running the analysis
    Now that everything is set up in the Capture program, we turn the analysis over to PSPICE. Start the simulation by choosing "Run" from the "PSPICE" menu or by clicking on the "run triangle", which is the third item in the second horizontal toolbar. After a few seconds (if there are no errors) the analysis will finish and SPICE will automatically launch Probe. You should see a window with an empty plot in it. Since we did an Transient analysis, the x-axis on the plot will be the time. If there are errors, you can get some clue to the nature of the problem by examining the text in the lower left box in the window.



     
  9. Plotting the data
    All that's left is to make the plot showing the calculated results. To make the plot, we must add a trace. From the "Trace" menu, choose the item "Add Trace..." (or click on the Add Trace item in the second toolbar ) and a dialog will appear. On the left side of the dialog is a list all of the circuit variables that can be plotted. (It may take some trial and error to determine what each of the variables represent.) On the right is a list of mathematical functions that can be utilized in making the plot. On the left, click on "V1(V2)" and "V(Vout)", which is the voltage of the pulse source and "Vout" output port. Click OK when ready. You should see a plot like the one below.





     

If you see the above curve, all has been done for this assignment.

This webpage is adapted from "http://tuttle.merc.iastate.edu/ee333/spice/pspicetutorial/basics/pspicebasics.htm"