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Unformatted text preview: EE 101A / Winter 10 Lab #7 Page 1 of 12 Lab 7: SPICE (For week of 3/8) You can use the PSpice simulator in the Lab, or the PSpice CD in the back cover of your Sedra & Smith textbook. 1. Motivation: The role of circuit simulation Another important tool for a circuit designer is the circuit simulation program. There are many such programs, and each is tailored to simulate at a specific level of the system hierarchy (transistor, logic gate, functional block, etc.). The one we will introduce you to is called SPICE, and is by far the most widely used transistor-level circuit simulator. When designing a circuit, the engineer often makes rough calculations to get a ball-park estimate of the circuit parameters. But soon after that, the engineer will put the circuit into SPICE or some other simulator to verify its functionality and optimize its performance. Such CAD (Computer-Aided Design) tools have become indispensable as circuits become more complicated, and the device models more complex. By using SPICE, an engineer can take into account many second-order effects that are hard to calculate by hand, and also see how the circuit performs across different device, voltage, and temperature ranges. This will increase the chance that the circuit will work the first time, and in manufacturing, will save a great amount of design effort, time, and money. Presently, a single engineering cycle of high-end ICs can cost a few million dollars. In this lab, we will learn the basics of SPICE simulations, and also learn about modeling circuit components. After all, the simulation is only as good as the models used for the various components. 2. Characterization & modeling of a MOSFET 2.1. SPICE basics There are many manuals and tutorials on SPICE, and you will have opportunities to use SPICE in other circuit courses here at Stanford. We intend this to be just an introduction so that you can easily learn more advanced features later on. Most SPICE versions will take as input a text file called the SPICE deck , which is a description of the circuit we want to simulate, along with some control statements that tell SPICE what type of analysis to perform. We will provide the SPICE decks needed for this lab, so that you can learn the basic rules of creating SPICE decks, and familiarize yourself with the general SPICE simulation environment. EE 101A / Winter 10 Lab #7 Page 2 of 12 2-1. Find the PSpice A/D Student icon and start the program (under PSpice Student ). 2-2. Open a new text file ( File New Text File ), which allows us to enter the SPICE deck. 2-3. Enter the following: * EE 101A MOSFET IV Curves * MOSFET M1 d g 0 0 hw5mos W=5u L=1u * Input Voltage Sources Vg g 0 0 Vd d 0 0 * MOSFET Model Statement .MODEL hw5mos NMOS VTO=0.5 KP=1m LAMBDA=0 * Control Statements .DC Vd 0 5 0.1 Vg 1 5 0.5 .PROBE .END Here are some rules & features to remember when writing SPICE decks: SPICE is not case-sensitive – capital letters are treated the same as lower case letters. SPICE is not case-sensitive – capital letters are treated the same as lower case letters....
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This note was uploaded on 03/30/2010 for the course EE 101A taught by Professor Wong during the Winter '08 term at Stanford.
- Winter '08