An Introduction To EDA Tools (Part 2)

BY Manu Prasad

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In part 1 of this article, we learnt about LiveWire and Multisim electronic design automation (EDA) tools. Let us now take a look at OrCAD and Proteus.

OrCAD

It is one of the most-popular EDA tools in industry. OrCAD is a suite of tools from Cadence for design, simulation and layout of PCBs. This software is mainly used by design engineers to create electronic schematics and electronic prints for manufacturing PCBs. It enables designing of a circuit from beginning to end. It is highly-customisable; we can alter the components and their characteristics based on our requirements.

It is one of the most-popular EDA tools in industry. OrCAD is a suite of tools from Cadence for design, simulation and layout of PCBs. This software is mainly used by design engineers to create electronic schematics and electronic prints for manufacturing PCBs. It enables designing of a circuit from beginning to end. It is highly-customisable; we can alter the components and their characteristics based on our requirements.

OrCAD comes with three main applications. Capture, the first application, is used to draw a circuit on the screen, known as schematic capture. It offers great flexibility when compared with traditional paper-and-pen drawing, as design changes can be incorporated without difficulty and error corrections can be done easily.

OrCAD comes with three main applications. Capture, the first application, is used to draw a circuit on the screen, known as schematic capture. It offers great flexibility when compared with traditional paper-and-pen drawing, as design changes can be incorporated without difficulty and error corrections can be done easily.
The second application, PSpice, simulates the captured circuit. We can analyse the circuit’s behaviour in different ways and verify that it performs as required.

The second application, PSpice, simulates the captured circuit. We can analyse the circuit’s behaviour in different ways and verify that it performs as required.

PCB Editor, the last, is used to design PCBs. Output of this is a set of files that can be sent to the manufacturer for PCB fabrication or to an electronics workshop. Go through these applications before using any of the tools, as it will improve your learning skills.

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PCB Editor, the last, is used to design PCBs. Output of this is a set of files that can be sent to the manufacturer for PCB fabrication or to an electronics workshop. Go through these applications before using any of the tools, as it will improve your learning skills.

The program used here is a version of Simulation Program for Integrated Circuit Engineering (SPICE), which was developed at University of California in Berkeley, USA, in the 1970s. For many years it has been the most-widely-used circuit simulator in the electronics industry. It has many versions, of which we will describe PSpice.

The program used here is a version of Simulation Program for Integrated Circuit Engineering (SPICE), which was developed at University of California in Berkeley, USA, in the 1970s. For many years it has been the most-widely-used circuit simulator in the electronics industry. It has many versions, of which we will describe PSpice.

There are three basic steps to be followed:

1. Draw an electronic circuit using Capture.
2. Simulate it with PSpice using specific models for the devices and analyse its behaviour with Probe.
3. Create basic design steps for the PCB using PCB Editor.

Following are the steps used in OrCAD (16.0 version) for simulation and PCB design:

1. Open OrCAD program on the computer. The file will be in the folder of installed software named OrCAD Capture.
2. Opening the tool will direct you to a Cadence product choice window. Select OrCAD Capture and click OK. It will lead you to a new window of Capture.
3. Open a new project from File menu (Fig. 12).

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Fig. 12: Creating a new project

4. Provide the details in the next window and select Analog or Mixed A/D (Fig. 13).

Fig. 13: New project window

5. Giving project details will lead to a new blank project schematic window. Place the components from option Place→Part. OrCAD library provides a large variety of components. Each component has its own library file. Add those library files to Place Part window using Add Library option.
6. Select the required components from Place Part window. Preview and other details are available in the same window and are visible when the component is selected (Fig. 14). You need to give the exact component name in the part’s place.

Fig. 14: Placing the components

7. After placing the components in the schematic, connect the terminals with a wire that can be selected from Place→Wires. Make sure that no parts are left open without connections.
8. Place markers at the corresponding (test) points of circuits where you need to observe the output. For selecting a marker, go to PSpice→Markers→Voltage Level (for voltage reading) as shown in Fig. 15.

Fig. 15: Circuit with test points

9. Simulation can be done by making a simulation profile. It can be done from New Simulation Profile option in PSpice menu. Give a profile name and click Create. This leads to a simulation setting window. We can give customisation for simulation in this window. In this particular example, select Analysis Type Time Domain (Transient). Give sufficient time to run and check Skip The Initial Transient Bias option. After giving inputs, click OK.
10. Select Run option from PSpice menu and give sufficient inputs. This opens a new simulation window in which you can verify the signals at test points (Fig. 16).

Fig. 16: Output window

11. Like in all other EDA tools, OrCAD components must also have their own footprint, which is the mechanical outline of the device on the PCB board. Check the property of the device by right-clicking on it. From Property window, check if all devices have their own footprints.
12. Click on your project name on Navigation window (with extension .dsn). Go to Tool→Design Rule Check. Give options as per needs and click OK. This step will check the design for errors, if any, and those will be shown in the log file. Make necessary corrections.
13. Now open PCB Editor from OrCAD folder on your computer. Got to File→New Drawing. Give a proper name and path (preferably in the folder where you created the project) of the file. Select Board Wizard. The wizard will direct you and give sufficient details in the process. Save the drawings.
14. Come back to the schematic OrCAD window and click on your design file. Then, go to Tools option in the menu and click Create Netlist. The programs communicate using files called netlists.
15. A new window will open. Check Create or Update PCB Editor and Create PCB Editor Netlist (Fig. 17). Save the input board file as .brd file that you created and saved in the folder. Give a name for the netlist file. Also, select Open Board option on PCB editor. Click OK.

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Fig. 17: Window for creating netlist

16. PCB editor will automatically open. In Place menu, select Manual option. Now, place all the elements on the side of the rectangular board, and drag and arrange these properly inside the rectangular board place. After arranging the components in a proper manner, without any overlapping, go to Route menu, then PCB router and click on Route Automatic. Routing will be automatically done. You can also do manual routing for better performance (Fig. 18).

Fig. 18: Placing the components

17. Go to Manufacture→Artwork. Give the corresponding options. Click on Create Artwork. If you go to the project folder, you will see a file with extension .art. You can print the file also for further manufacturing process.
18. Save your work before closing the window.

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