ECE 2006 University of Minnesota Duluth Lab 3 ECE Department Page 1 February 5/7, 2007 Introduction to Pspice® 1. Objectives The learning objectives for this laboratory are to give the students a brief introduction to using Pspice® as a tool to analyze circuits and also to demonstrate the use of a small signal model as an example of a dependent source. The latter is done by constructing a simple voltage follower circuit using a transistor to amplify an input current. 2. Background The Simulation Program with Integrated Circuit Emphasis (SPICE) was developed in the Department of Electrical Engineering and Computer Science at the University of California at Berkeley. SPICE is capable of performing DC, AC, or transient analysis. It was originally designed to analyze a circuit that was solely defined by a series of statements that constituted a “Net list”. With the advent of personal computers, the graphical user interface of the program evolved into its current state (The ‘P’ in PSpice® comes from Personal Computer). In the current environment, users can also enter circuit diagrams in a schematic layout (once simulated a netlist is still generated). This latter technique will be utilized in this and subsequent labs for the purpose of simulating and analyzing circuits. In addition to this lab, the student version of PSpice® is available on the computers in MWAH 102 and is also available to download on-line (see the course syllabus for directions). For the remainder of this lab “Pspice®” will refer to the student version of the program. 3. Prelab Calculate Vx and Ix in Circuits 0 and 1 (Figures 1 & 4). Record the values in Table 1. 4. Procedure 4.1. Equipment • PSpice® on Personal Computer • Agilent E3631A DC Power Supply • Fluke 8050A Digital MultiMeter (DMM) • (2) 1 kΩ Resistors • (1) 2N2222 Transistor 4.2. Pspice® Tutorial PSpice® is a window-based program and can be accessed from the program menu under the grouping of “PSpice Student.” Since we will be using the schematic entry option, open this up first (called “Schematics” in the program grouping).ECE 2006 University of Minnesota Duluth Lab 3 ECE Department Page 2 February 5/7, 2007 As an example, we will construct the circuit shown in Figure 1. +–+–12 V3 MΩ900 Ω1 kΩ3 V+–+–+–+–12 V3 MΩ900 Ω1 kΩ3 V Figure 1: Example (Circuit 0) To construct the circuit shown, you will need to: 1. Insert each part, 2. Assign the appropriate value, and 3. Connect the parts by drawing wires. 4.2.1. Inserting and Manipulating Parts Parts can be inserted by clicking on the “Get New Part ...” option under the “Draw” menu (you can alternately use [Cntl + G] as a shortcut or click on the button with a gate and set of binoculars). For now, all parts that we will need should be listed in the “Part Browser Basic” window that subsequently pops up. For the parts in Figure 1, you will need to choose (by highlighting) the appropriate part and then clicking on the “Place & Close” button. A list of commonly used parts is listed in Figure 2. Figure 2: Commonly Used Parts and Their Library Abbreviations To place a part, simply drag the cursor to the desired area of the schematic and then left click. The program allows you to place multiple instances of the same part with subsequent left clicks. When you have finished placing all the desired instances of a particular part, clicking the right mouse button will allow you to return to the selection cursor (white arrow). Another command that will be useful when drawing schematics is the “Rotate” command which can be found in the “Edit” menu or by using the shortcut [Cntl + r]. First select the part (the program will highlight it in red), and then use the “Rotate” command. + Vx – IxECE 2006 University of Minnesota Duluth Lab 3 ECE Department Page 3 February 5/7, 2007 Once you have entered the two voltage sources and 3 resistors into your schematic, you will need to modify the default values. This can be done directly by double-clicking on the value or by double-clicking on the part and then selecting the attribute from the subsequent list. When changing the value, you will need to use the appropriate suffix. The list of parameter suffixes that PSpice® recognizes is listed in Figure 3. It is important to note that PSpice® is not case sensitive. This means that ‘Meg’ = ‘MEG’ = ‘meg’. Figure 3: Parameter Suffixes In addition to the above steps, you will need to connect your components by drawing wires. This can be done by choosing “Wire” under the “Draw” menu or by using the shortcut [Cntl + w]. To connect two points, simply click on one point and then the other. If the wire needs to contain more than one 90 degree angle, you can click on a point in the grid and the program will bend the wire there and allow you to continue stretching it in a new direction. To exit the mode, again use the right-click of the mouse. 4.2.2. Simulating and Analyzing Voltages and Currents Next you should save your schematic (*.sch). After saving, you can then simulate your circuit(s) by choosing “Simulate” under the “Analysis” menu or by pressing F11 (the program will prompt you to save the schematic if you have not already done so). At this point, the program should give you an error. This occurs because the circuit is not yet grounded (it is good to make note of the error for future reference as this is a common mistake). To fix the error, insert the part called GND_Earth. The circuit should now successfully simulate (and will pop up the A/D window). Make sure you are in the schematic window and look in the upper right portion of the tool bar. There should be ‘V’ and an ‘I’ button that will display the voltage at all nodes (in green) and the currents through all elements (in blue). You should be able to now click on each green or blue marker individually and see a dashed line indicating what node/element the measurement is assigned to. It is important to note the direction of the current when selecting the blue measurements. You can also toggle currents