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1. In this simple DC circuit there are no time varying voltages or currents. Thus, we only need to find the values of the dc voltages and currents throughout the circuit. This is referred to as a DC Bias analysis. 2. Choose the menu option: PSPICE ! New Simulation Profile. A dialog box will open. Type in the name of the simulation as "DC Bias".
factors used in PSPICE Letters immediately following a number that are not scale factors areignored as are letters immediately following a scale factor For example 10 10v 10Hz and 10Aall represent the same number as do 2 5m 2 5MA 2 5msec and 2 5Mohms Do NOT includespaces in your values For example 15ohms is correct but 15 ohms is notTable 1 PSPICE Scale FactorsSymbol Exponential FormNote the difference between the use of M and MEG as a scale factorStarting a New PSPICE FileTo learn the fundamental steps of running a PSPICE simulation we will begin with the simpleresistive circuit shown in figure 1Figure 1 Resistive Circuit1 On the computer s Desktop screen click on Start move the cursor to Programs Orcad16 2 Capture CIS Depending on the directory names that you used during theinstallation these titles may read differently No license will be found if you are running thedemo version Indicate that you want to start using the demo license2 The Orcad Capture window should open Click on File New Project3 The New Project dialog box should open4 Type the name of your circuit in the Name box and indicate the path to the directory inwhich you want to store your file under Location5 Click on the radio button next to Analog or Mixed A D then click OK6 The Create PSPICE Project dialog box will appear Select Create a blank project and7 A schematic entry window will appear The screen should now look similar to that in Figure2 Due to the differences in versions your display may have a different appearanceFigure 2 Schematic Entry WindowFigure 3 Place Part Dialog BoxPlacing the Parts1 Select Place Part The place part dialog box will open as shown in figure 3 again itmay have a different appearance In the lower left hand corner a list of the libraries thathave been loaded will appear Your list may be different that the one shown in the figure Ifthis is the first time you are running PSPICE on a particular computer all of the libraries maynot appear At a minimum you should install the libraries analog eval source and specialTo add a Library click on the Add Library Icon a small square above the library list inversion 16 2 The libraries listed above can be found in the following directorytools capture library pspice demo or something similarAdd each of the four libraries listed above2 In the Place Part dialog box click on the Analog library then click on the R in the PartList A drawing of a resistor should appear in the lower right corner Press Enter Return3 Move your mouse pointer over the schematic window A resistor should be following thepointer Drag the resistor to the desired location and click once to place it4 Drag to the next location to place the second resistor and click to place it5 Since we want the third resistor to be vertical right click the mouse button and selectRotate from the popup menu Then click to place the third resistor see figure 4Figure 4 Resistor Placement6 Once all of the resistors have been placed right click the mouse button and select EndMode from the pop up menu This will cause the resistor to disappear Alternatively youmay enter ESC7 Next we need to add the DC voltage source Select the Source library from the Place Partwindow and the part VDC Place this on the schematic as you did with the resistors8 Every circuit that is simulated on PSPICE must have a ground node indicated This is doneby entering the ground symbol To place the ground select Place Ground or click on theground symbol on the toolbar Select the Source library and the ground part labeled 0It is very important that you use this particular ground or your simulation will not runThe first time you use this ground you may need to add the Source library from the PlaceGround window Place the ground as shown in figure 5Figure 5 Circuit Element PlacementWiring the schematic1 Select the Place Wire button from the toolbar2 Drag the cross hair pointer to the positive end of the VDC source Click on it3 Move the cross hair pointer to the left terminal marker of the first resistor Click on it4 Repeat the procedure until all components are connected5 Click the right mouse button Select End Wire and click on it Your schematic should nowappear as the one in figure 6Figure 6 Wired CircuitSetting the component values1 All of the resistor values default to 1K To change a resistor value double click on theresistor value The Display Properties box appears2 In the Value box type in the desired resistance Make sure to use the appropriate suffix aslisted in the PSPICE introduction Click on OK3 Repeat for all resistors4 Using the same procedure change the value of the dc voltage source to 10V The circuitshould now appear as the one in figure 7Figure 7 Circuit with Component ValuesSpecifying the type of analysis1 In this simple DC circuit there are no time varying voltages or currents Thus we only needto find the values of the dc voltages and currents throughout the circuit This is referred to asa DC Bias analysis2 Choose the menu option PSPICE New Simulation Profile A dialog box will openType in the name of the simulation as DC Bias Click Create3 The Simulations Settings dialog box opens Under Analysis Type select Bias Point and4 Save your circuitRunning the Simulation1 Select the menu option PSPICE Run The simulation will run and the simulationwindow will open as shown in figure 82 In the lower left corner of the window is an output text section that displays the progress ofthe simulation and any errors that were encountered The remaining sections will bediscussed later3 In this example we will view the results of the simulation as a SPICE output file Select themenu option View Output File A text file will appear in the upper window Figure 9shows the output and describes each section Note that the default output includes thevoltage at each node and the current flowing through each voltage source For example theinitial circuit listing in the output shows us that the 3K resistor is connected between nodesN00132 and N00159 The output indicates that the voltages at those two nodes are 8 and 5volts respectively Thus this resistor has 3 volts across itFigure 8 Simulation Window03 29 01 13 17 18 PSpice Lite Mar 2000Profile SCHEMATIC1 dc bias C Program Files OrcadLite project1 SCHEMATIC1 dc bias simCIRCUIT DESCRIPTIONCreating circuit file project1 SCHEMATIC1 dc bias sim cirWARNING THIS AUTOMATICALLY GENERATED FILE MAY BE OVERWRITTEN BY SUBSEQUENTSIMULATIONSLocal LibrariesFrom PSPICE NETLIST section of C Program Files OrcadLite PSpice PSpice ini filelib nom libAnalysis directivesPROBE V I W D NOISEINC project1 SCHEMATIC1 netINCLUDING project1 SCHEMATIC1 netsource PROJECT1 This section is the listing that describes theR R1 N00102 N00132 2KR R2 N00132 N00159 3Kcircuit that you have drawn Note that thereR R3 0 N00159 5K is one line for each component This lineV V1 N00102 0 10V lists the component values and the numbersof the nodes that it is connected betweenRESUMING project1 SCHEMATIC1 dc bias sim cir03 29 01 13 17 18 PSpice Lite Mar 2000Profile SCHEMATIC1 dc bias C Program Files OrcadLite project1 SCHEMATIC1 dc bias simSMALL SIGNAL BIAS SOLUTION TEMPERATURE 27 000 DEG CNODE VOLTAGE NODE VOLTAGE NODE VOLTAGE NODE VOLTAGEN00102 10 0000 N00132 8 0000 N00159 5 0000This section lists each nodeVOLTAGE SOURCE CURRENTSNAME CURRENTnumber and the correspondingvoltage at that node It also listsV V1 1 000E 03 the current flowing through eachvoltage sourceTOTAL POWER DISSIPATION 1 00E 02 WATTSJOB CONCLUDEDTOTAL JOB TIME 13Figure 9 PSPICE Output File4 Return to the window with your schematic Select PSPICE Bias Points Enable BiasVoltage Display if it is not already selected The dc bias voltages will now be displayeddirectly on your diagram eliminating the need to view the output file at all See figure 10Experiment with displaying the current and power valuesFigure 10 Schematic with Bias Voltage DisplayCurrent SourcesA DC independent current source can be found in the parts list as IDC This is similar to thevoltage source used above except the current is held at a specified valueDisplaying Currents and PowerIn addition to displaying voltages current and power values found in the bias point analysis canalso be displayed Enter the schematic shown in Figure 11 Perform the DC bias point analysisSelect PSPICE Bias Points Enable Bias Power Display Confirm that the power valuesdisplayed are correctFigure 11 DC Analysis Problem