Analog Design and Simulation using OrCAD Capture and PSpice provides step-by-step instructions on how to use the Cadence/OrCAD family of Electronic Design Automation software for analog design and simulation. Organized into 22 chapters, each with exercises at the end, it explains how to start Capture and set up the project type and libraries for PSpice simulation. It also covers the use of AC analysis to calculate the frequency and phase response of a circuit and DC analysis to calculate the circuits bias point over a range of values.
The book describes a parametric sweep, which involves sweeping a parameter through a range of values, along with the use of Stimulus Editor to define transient analog and digital sources. It also examines the failure of simulations due to circuit errors and missing or incorrect parameters, and discusses the use of Monte Carlo analysis to estimate the response of a circuit when device model parameters are randomly varied between specified tolerance limits according to a specified statistical distribution. Other chapters focus on the use of worst-case analysis to identify the most critical components that will affect circuit performance, how to add and create PSpice models, and how the frequency-related signal and dispersion losses of transmission lines affect the signal integrity of high-speed signals via the transmission lines.
Practitioners, researchers, and those interested in using the Cadence/OrCAD professional simulation software to design and analyze electronic circuits will find the information, methods, compounds, and experiments described in this book extremely useful.
- Provides both a comprehensive user guide, and a detailed overview of simulation
- Each chapter has worked and ready to try sample designs and provides a wide range of to-do exercises
- Core skills are developed using a running case study circuit
- Covers Capture and PSpice together for the first time
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About the Author
His primary research interest is in the use of Functional Electrical Simulation (FES) for the restoration of bladder function and restoration of gait in stroke and spinal cord injured patients. His research focuses on the design and development of implantable medical systems. His recent book 'Analogue Design and Simulation using OrCAD Capture and PSpice', also published by Elsevier, has sold worldwide to highly acclaimed reviews in numerous prestigious electronic engineering journals such as EDN and Electronic Times and is officially endorsed by Cadence Design Systems.
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Analog Design and Simulation using OrCAD Capture and PSpice
By Dennis Fitzpatrick
NewnesCopyright © 2012 Elsevier Ltd.
All right reserved.
Chapter OneGetting Started
Chapter Outline 1.1 Starting Capture 1 1.2 Creating a PSpice Project 2 1.3 Symbols and Parts 7 1.3.1 Symbols 7 1.3.2 Parts 8 1.4 Design Templates 10 1.5 Summary 12 1.6 Exercises 13 Exercise 1 13 Exercise 2 15 1.7 Extra Library Work 17
Those of you who are familiar with setting up projects and drawing schematics in Capture may want to skip this chapter, as it has been written for those of you who have little or no experience of using Capture. This chapter will describe how to start Capture and how to set up the project type and libraries for PSpice simulation.
At the end of each chapter there are some exercises to do and as you go through the book, each chapter will build upon the exercises from previous chapters.
1.1 STARTING CAPTURE
Circuit diagrams for PSpice simulation are drawn in either Capture or Capture CIS schematic editor. The CIS option, which stands for Component Information System, allows you to select and place components from a component database instead of selecting and placing components from a library. For this book, it does not matter whether the circuits are drawn in Capture or Capture CIS.
If you have the OrCAD software installed, launch Capture or Capture CIS, by clicking on:
Start > Program Files > OrCAD xx.x > Capture
Start > Program Files > OrCAD xx.x > Capture CIS
where xx.x is the version number, e.g. 10.5, 11.0, 15.5, 15.7, 16.0, 16.2, 16.3 or 16.5.
At the time of writing this book, the current version is 16.5 and is started by:
Start > Program Files > Cadence > Release 16.5
If you have the Cadence software installed, the tools are installed under the Allegro platform name. In this case, only Capture CIS is available and is branded as Design Entry CIS:
Start > Program Files > Allegro SPB xx.x > Design Entry CIS
1.2 CREATING A PSPICE PROJECT
New designs started in Capture will automatically create a project file (.opj) which will reference associated project files such as the schematics, libraries and output report files.
Before the circuit diagram is drawn, the project type and libraries required for the project need to be set up. First of all a new project is created by selecting from the top toolbar:
File > New > Project
In the New Project window (Figure 1.1), you enter the name of the project and then you have a choice of one of four project types:
Analog or Mixed A/D is used for PSpice simulations.
PC Board Wizard is used for schematic to PCB projects.
Programmable Logic Wizard is used for CPLD and FPGA designs.
Schematic is used for schematic and wiring diagrams.
When you select a Project type, the Tip for New Users gives a brief explanation of the project type. For PSpice projects, select Analog or Mixed A/D. This will activate the PSpice menu on the top toolbar in Capture.
It is recommended that a new directory location (folder) is created for each new project. This can be done by clicking on the Browse ... button shown in Figure 1.1, which opens up the Select Directory window shown in Figure 1.2.
By selecting the Create Dir ... button, the Create Directory window (Figure 1.3) appears, which allows you to name the directory (folder).
The created folder, PSpice Exercises in this example, will appear in the Select Directory window. However, you must highlight and select the folder by clicking twice with the left mouse button, which will show the 'open' yellow icon as shown in Figure 1.4. A further subdirectory or folder can be created by clicking on the Create Dir ... in the Select Directory window button and following the same procedure above.
The project folder location will then appear in the Location box of the New Project window (see Figure 1.1).
An alternative method of creating the project folder is to type in the folder location directly into the Location box in the New Project window in Figure 1.1 and Capture will automatically create the folder.
The next window to appear is the Create PSpice Project window, which sets up the project for PSpice simulation (Figure 1.5).
The pull-down menu option allows you to select preconfigured Capture-PSpice libraries for the project. The most commonly used option for new projects is Simple.opj, which adds the following five default libraries to the project:
These libraries contain the most commonly used parts for PSpice projects and are recommended for new projects.
There is also an option to create updated versions of an existing project, i.e. to create a newer version 2 based upon the original version 1 project. In the Create PSpice Project Window (Figure 1.5), select the function Create based upon an existing project and then Browse to select an existing project. This will copy the existing project and all its associated files into the new project. This is similar to using the File > Save As function.
If the Create a blank project option is selected, then no Capture-PSpice libraries are added to the project. The libraries can be added later. This will be demonstrated in one of the exercises at the end of this chapter.
When a new project is created, a Project Manager window is created (Figure 1.6) which shows the absolute path to the libraries. Remember that these are Capture symbol libraries which define the graphics for the parts. They are not the PSpice model libraries. The Capture libraries are installed by default and can be found, depending on the OrCAD or Cadence software version you are using, for example, at:
<software install path> OrCad > OrCAD_10.5 > tools > capture > library > pspice
<software install path> Cadence > SPB_16.3 > tools > capture > library > pspice
Normally the <software install path> is the C: drive.
Alternatively, click on the Project manager icon [??] or [??].
1.3 SYMBOLS AND PARTS
Before drawing a schematic diagram, it is useful to know the difference between a part and a symbol. Symbols differ from parts in that they are not placed from the Place Part menu in Capture. You have to select the symbol from the Place menu (Figure 1.8).
The Place menu also shows the corresponding shortcut keys. For example, to place a Power symbol, press F and the Place Power menu appears as shown in Figure 1.9.
Wires connected to symbols take on the name of the symbol. For example, to define a wire to be connected to zero volts, you place a '0' symbol. To define a +5 V connection you can use a VCC_CIRCLE symbol and rename it +5 V. All wires connected to the +5 V symbol will take on a net name of +5 V. A net is a wire connection. There are many different symbols you can use to define the power and grounds connections and you can rename them accordingly.
In the Place Power menu in Figure 1.9, a VCC_CIRCLE symbol has been selected and its name has been changed to +5 V. Any wires (nets) connected to +5 V will take on the net name +5 V.
Other symbols include hierarchical ports and off-page connectors which allow signals to be connected together throughout the design. These will be discussed in Chapter 20.
There are two symbol libraries, source and capsym. Capsym contains all the analog ground and power symbols, while source, which also contains the analog 0V symbol, contains the digital $D_HI and $D_LO symbols, which are used to set a digital level of 'hi' or 'lo' on a wire or pin of a digital device.
To place a part, select Place > Part. Figure 1.10a shows the Place Part menu for version 16.0 and Figure 1.10b shows the Place Part menu for version 16.3.
Although the two menus look different they have the same functionality in that they display the list of libraries available and the parts available in the libraries; and they both provide a part search function. In Figure 1.10a, only the analog library has been highlighted and so only those parts for that library are shown in the Part List.
In Figure 1.10b, all the libraries have been highlighted and so you see the name of the part and which library it comes from. If you place the cursor over any part in the Part List, a tool tip rectangular bar appears showing the absolute path to the library part.
In the Place Power or Place Ground window (Figure 1.11) there is a source library which contains only the digital HI, digital LO and ground 0 V symbols.
To recap, symbols are placed from the Place menu and parts are placed from the Place > Part menu. Also note that both Part libraries and Symbol libraries have an .olb extension and are the Capture graphical parts.
1.4 DESIGN TEMPLATES
From version 16.3 onwards, Design Templates have been added, which are complete electronic circuits and topologies including simulation profiles for analog, digital, mixed and switched mode power supplies. You can select any of these templates from the pull-down menu in the Create PSpice Project window when you create a new project (Figure 1.12).
Figure 1.13 shows the Design Template for a Single Switch Forward Converter which includes the schematic and explanatory text.
Figure 1.14 shows the Project Manager created for a PSpice project and the checks that can be made to ensure that a PSpice project has been set up correctly. One common mistake is not selecting and highlighting the project folder that is created (see Figure 1.4).
Another common mistake when creating a project is that the wrong project type has been created; for example you see PCB instead of Analog or Mixed A/D in the Project Manager title. One way around this is to create a new project (of the correct type) and copy and paste the .dsn file from the previous Project Manager into the new Project Manager. From version 16.3 onwards, you can change the project type by highlighting Design Resources in the Project Manager and rmb > Change Project Type (Figure 1.15).
You will create a new PSpice project as discussed in Section 1.2 and name it resistors. The project will be created in a folder called, for example, C:\PSpice\resistors and will be configured with the simple five default libraries.
1. Select File > New > Project. Enter resistors for the Name and select Analog or Mixed A/D. In Location, enter C:\PSpice exercises\resistors or you can use your own folder location. Check your entries with Figure 1.16 and then click on OK.
2. In the Create PSpice Project window, select simple.opj as shown in Figure 1.17 and click on OK.
3. The Project Manager window will appear as shown in Figure 1.18.
4. Expand resistors.dsn by double clicking on it to open the SCHEMATIC1 folder (Figure 1.19).
5. Double click on SCHEMATIC1 to open PAGE1 and double click on PAGE1 to open up the schematic page (Figure 1.20).
6. When you first open the schematic page, you will see some preplaced text and two voltage sources preplaced. Delete the sources and text by drawing a box around the sources and text and pressing the delete key.
Draw the resistor network shown in Figure 1.21.
1. To place a resistor, select Place > Part and select an R from the analog.olb library. Double click on the R and the resistor will attach to the cursor. In previous versions, click on OK and the Place Part menu disappears. From release 16.0 onwards, when you double click on a part or click on the Place Part [??], the menu will remain open.
When you place the first resistor in the schematic, another resistor will be attached to the cursor; click rmb > Rotate or press R on the keyboard and place the second resistor. To exit place part mode, rmb > End Mode or press escape. Whenever a part is selected, there is an rmb context menu for place part options. P is the hotkey to place a part or you can select the Place Part icons, depending on which software release you have [??] or [??].
2. For R1 and R2, double click on the default resistor value of 1k and change its value to 10 R.
Excerpted from Analog Design and Simulation using OrCAD Capture and PSpice by Dennis Fitzpatrick Copyright © 2012 by Elsevier Ltd.. Excerpted by permission of Newnes. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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Table of Contents
1.0 Getting Started
2.0 DC Bias Point Analysis
3.0 DC Sweep Analysis
4.0 AC Sweep Analysis
5.0 Parametric Sweep
6.0 Stimulus Editor
7.0 Transient Analysis
9.0 Format of a PSpice Netlist
10.0 Monte Carlo
11.0 Worst Case Analysis
12.0 Create Hierarchical Designs
13.0 Analog Behaviourial Models
14.0 Performance Analysis
15.0 Noise Analysis
16.0 PSpice Models
17.0 Digital Simulation
18.0 Mixed Simulation