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| =Analog IC design flow using Cadence from basics(Schematic capture, Netlist extraction, Simulating using ELDO, Layout, Signoff Layout)= | | = IC design flow using Cadence = |
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| ==Starting up==
| | We have access to several silicon technologies from different foundries |
| This tutorial will start from very basics in analog IC design then take you through the whole analog IC design process using a combination of cadence and mentor tools.
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| Here is the outline of the analog IC design flow:
| | * 130nm CMOS process from Taiwan Semiconductor Manufacturing: '''[[ TSMC 130nm process ]]''' |
| 1. Schematic capture (Cadence tool)
| | * 130nm SiGe process from Innovations for High Performance Microelectronics: '''[[ IHP 130nm process ]]''' |
| 2. Netlist extraction from schematic
| | * 350nm CMOS process from Austria Mikro Systeme: '''[[ AMS 350nm process ]]''' |
| 3. Simulating using ELDO simulator and viewing results with EZWAVE (ELDO is a Mentor Graphic's tool for netlist level simulations)
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| 4. Layout using Cadence
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| 5. Signoff layout (DRC, LVS and parasitic extraction) using Calibre (Calibre is a Mentor Graphic's tool)
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| ssh -X mikroserver2
| | = Design entry using schematic capture = |
| csh
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| source /prog/cadence/cadence_init.csh
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| ams_cds_start
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| Virtuoso Mixed Signal Design Environment should now start up.
| | * Make sure you have set correct library. |
| | * Make sure you run virtuoso from the same folder as your 'cds.lib'-folder ('~/LIBRARY_VENDOR/') |
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| In the log window, choose "File > New > Library".
| | [[Design entry|Virtuoso schematic editor]] |
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| In the "New Library" dialog box, you must give the library a name (for example TORLIB, as I did). You must also specify a technology file. Here you choose "Attach to an existing technology library". Then click the OK button. When asked for technology, choose TECH_C35B4.
| | = Simulation = |
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| After successfully creating the new library, it is time to create your first design. In the log windowox, choose "File > New > Cellview". In the "Create New File" dialog box, you must give the design a name. You must also specify which library the design belongs to, and here you specify the library that you have just created. Choose to open the cell with "Schematics XL" and add a checkmark to always use this application if it is not checked.
| | [[Testbench|Virtuoso Testbench]] |
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| Now click OK, and the Virtuoso Schematic Editor should pop up. We will now draw a simple inverter design, as shown in the picture:
| | = Layout = |
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| [[File:virtuoso_schematic_editor.png|400px]] | | [[Layout XL and IHP SG13S]] |
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| ==Entering the design== | | =Helpful stuff= |
| To create the inverter design, do the following:
| | [[MikroserverSetup]] - setup for easy connection to the mikroservers and Cadence Virtuoso |
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| 1. Press 'i' or click on the "Instance" icon to invoke the transistors. The "Add Instance" dialog box will now pop up. In the "Library" field, click "Browse" to open the "Library Browser". In the library browser, choose "PRIMLIB" as library, "nmos4" (for n-type transistor) or "pmos4" (for p-type transistor) as cell and "spectreS" as view. The cell is placed in the schematic by moving the cursor to the desired location and clicking the left mouse button.
| | [[ Transistor operating point printer ]] - Script to extract transistor operating point parameters after simulation. |
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| 2. To insert the voltage sources, pick the "vdc" cell from the "analogLib" library. Add one connected to vdd and gnd and one connected to the input.
| | [[DCoperatingparameters]] - Guide for showing transistor operating points in the schematic |
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| 3. To insert the ground and vdd nets, pick the "vdd" and "gnd" cells from the "analogLib" library. Here the view name should be "symbol", not "spectreS" (in fact, "symbol" is the only available option).
| | [[ ADEXL-butterfly-curves ]] - Howto make DC butterfly curves easily. |
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| 4. To connect the symbols, press 'w' or click the "Wire (narrow)" icon. Then use the left mouse button to click the nodes togeter, two by two.
| | [[Category:Mikroelektronikk]] [[Category:Integrated_Circuts]] |
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| 5. To remove an instance or a wire, left click at the instance or wire that you want to remove, then press the "Delete" button on the keyboard.
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| 6. To insert a pin, press 'p'. Choose a name for the pin in the dialog that occurs and click on the schematic to place it. Create one input and one output.
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| 6. To change the properties of the icons, press 'q' or click at the "Properties" icon. Then click at the instances or nets that you want to modify. For the vdc source connected between vdd and gnd, set the "DC voltage" property to 3.3.
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| 7. To check and save the schematic, press 'X' or click the "Check and save" icon. Make sure you get no errors or warnings. Then open "Launch > ADE GXL" and press create new view. The "Virtuoso Analog Environment" should now come up.
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| ==Simulating the design==
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| 8. Choose "Create > Test..." select the cell to simulate.
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| 11. Choose "Outputs > To be plotted > Select on Schematic". Click at the "vdc" node connected to the inverter input, the drain node of the nmos transistor and the net connected between the drain nodes of the nmos and pmos transistor.
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| 12. Choose "Analyses > Choose". We will now run a dc analysis to obtain the DC transfer characteristics of the inverter. Choose "Component parameter" as your sweep variable. Then click at "Select component". In the schematic, click at the input "vdc" instance. In the "Select Component Parameter" dialog box, choose dc as your sweep parameter. The sweep range should go from 0 to 3.3.
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| [[File:select_comp_parameter.png|300px]] | |
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| The analog environment should now look like this:
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| [[File:analog_env_2.png|500px]]
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| 13. Choose "Simulation > Debug". The outputs should look like this:
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| [[File:plot_output_dc.png|600px]]
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| To save your simulation settings, choose "Session > Save state" to save your state information under whatever file namn you want. In a later session, you can reload your saved states using "Session > Load state".
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| ==Generating a Symbol==
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| Finally, we want to generate a symbol for our inverter. This symbol is needed if we want to use our inverter design inside another design (hierarchical design methodology).
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| Choose "Create -> Create Cellview -> From Cellview".
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| Press OK in the dialog that occurs.
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| The pins should allready be connected to the right positions in the symbol generator, so press ok here also and ths symbol editor will occur.
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| Press the red X and delete the precreated green square. Use the line tool and the circle tool to create the inverter symbol-
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| [[File:symbol.png|400px]]
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| Save it by clicking the "Save and check" symbol or pressing 'shift+X'.
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| [[Category:Mikroelektronikk]] | |
