Difference between revisions of "Tutorials:Cadence:SchematicSimulationDCAnalysis"

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(Created page with "= Schematic Simulation: Creating a Test File for Simulating an Inverter = Now that we have built an inverter, we need to simulate it to show that our design is valid. First w...")
 
 
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= Schematic Simulation: Creating a Test File for  Simulating an Inverter =
 
= Schematic Simulation: Creating a Test File for  Simulating an Inverter =
  
Now that we have built an inverter, we need to simulate it to  show  that our design is valid. First we need to create a new cell in our CSE463library  for  testing the inverter.  In the Library Manager, highlight the  test  library and left click on Library Manager:<strong>File-&gt;New-&gt;Cell View. </strong>
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Now that we have built an inverter, we need to simulate it to  show  that our design is valid. First we need to create a new cell in our CSE463library  for  testing the inverter.  In the Library Manager, highlight the  test  library and left click on Library Manager:'''File &rarr; New &rarr; Cell View'''.
  
 
In the Cell Name type inv_test and in the View Name type  schematic.  Left click on OK.
 
In the Cell Name type inv_test and in the View Name type  schematic.  Left click on OK.
  
<img src="images/cadence_img/schematic_TestInv.gif" alt="add_test" width="316" height="336">
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: [[File:Tutorials-Cadence-Schematic_TestInv.gif]]
  
 
A new schematic editing tool will appear. You are  going  to instance the inverter that was previously created and connect its  input  pin to voltage source. The output pin will be connected to a  capacitor.
 
A new schematic editing tool will appear. You are  going  to instance the inverter that was previously created and connect its  input  pin to voltage source. The output pin will be connected to a  capacitor.
  
Left click <strong>Editing:Add-&gt;Instance</strong>. Click  on the <strong>Library</strong> pull down menu and select  the <strong>CSE463</strong> library. Select the <strong>inv</strong> cell. The Component Browser window should look like the one bellow.
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Left click '''Editing:Add-&gt;Instance'''. Click  on the '''Library''' pull down menu and select  the '''CSE463''' library. Select the '''inv''' cell. The Component Browser window should look like the one bellow.
  
<img src="images/cadence_img/schematic_TestInv_ComponentBrowser.gif" alt="add_inv1" width="226" height="424">
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: [[File:Tutorials-Cadence-Schematic_TestInv_ComponentBrowser.gif]]
  
Place the inverter in the middle of the editing  window.  Note: you can press <strong>F3</strong> key while you have selected the symbol you want to place and the <em>Add</em> <em>Instance</em> window will appear. In this window, you can edit some of the properties of the symbol if applicable.
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Place the inverter in the middle of the editing  window.  Note: you can press '''F3''' key while you have selected the symbol you want to place and the ''Add Instance'' window will appear. In this window, you can edit some of the properties of the symbol if applicable.
  
Now we want to add voltage DC sources. Left Click <strong>Editing:  Add-&gt;Instance</strong>.  In<strong> NCSU_Analog_Parts </strong>library; you will find <em>vdc</em><em></em> sources. Place them in  the test circuit.  Left Click <strong>Editing:Add-&gt;Instance.</strong>   In <strong>NCSU_Analog_Parts </strong>library, under <em>Voltage_Sources</em> categorie, you will find <em>vdc </em>source. Place them in  the test circuit. The Component Browser should look like the one bellow:
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Now we want to add voltage DC sources. Left Click '''Editing:  Add &rarr; Instance'''.  In '''NCSU_Analog_Parts''' library; you will find ''vdc'' sources. Place them in  the test circuit.  Left Click '''Editing:Add &rarr; Instance.'''   In '''NCSU_Analog_Parts''' library, under ''Voltage_Sources'' category, you will find ''vdc'' source. Place them in  the test circuit. The Component Browser should look like the one below:
  
<img src="images/cadence_img/schematic_TestInv_ComponentBrowserVDC.gif" alt="add_vdc" width="226" height="472">
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: [[File:Tutorials-Cadence-Schematic_TestInv_ComponentBrowserVDC.gif]]
  
Select <em>Vdc</em> and  Add Instance window will appear. In the DC Voltage  field  enter <strong>5V</strong>. This window should appear as such:
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Select ''Vdc'' and  Add Instance window will appear. In the DC Voltage  field  enter '''5V'''. This window should appear as such:
  
<img src="images/cadence_img/schematic_TestInv_AddInstanceVDC.gif" alt="add_vdc" width="386" height="495">
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: [[File:Tutorials-Cadence-Schematic_TestInv_AddInstanceVDC.gif]]
  
 
Place the symbol to the left of the inverter.
 
Place the symbol to the left of the inverter.
  
Now we want to add global ground and power lines. Left Click <strong>Editing:  Add-&gt;Instance</strong>.  In <strong>NCSU_Analog_Parts </strong>library, under <em>Supply_Nets</em> categorie, you will find <em>vdd</em> and <em>gnd</em> sources. Place them in  the test circuit. The Component Browser should look like the one below.
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Now we want to add global ground and power lines. Left Click '''Editing:  Add &rarr; Instance'''.  In '''NCSU_Analog_Parts''' library, under ''Supply_Nets'' category, you will find ''vdd'' and ''gnd'' sources. Place them in  the test circuit. The Component Browser should look like the one below.
  
<img src="images/cadence_img/schematic_TestInv_ComponentBrowserGND.gif" alt="gg" width="226" height="440">
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: [[File:Tutorials-Cadence-Schematic_TestInv_ComponentBrowserGND.gif]]
  
Once you select the NCSU_Analog_Parts selection and select Supply_Nets, you will find <em>gnd</em> and <em>vdd</em> symbols. The Add Instance windows for <em>vdd</em> and <em>gnd</em> should look like the ones below:
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Once you select the NCSU_Analog_Parts selection and select Supply_Nets, you will find ''gnd'' and ''vdd'' symbols. The Add Instance windows for ''vdd'' and ''gnd'' should look like the ones below:
  
<img src="images/cadence_img/schematic_TestInv_AddInstanceVDD.gif" alt="add_vdd" width="386" height="240">
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: [[File:Tutorials-Cadence-Schematic_TestInv_AddInstanceVDD.gif]]
  
<img src="images/cadence_img/schematic_TestInv_AddInstanceGND.gif" alt="gnd" width="386" height="240">
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: [[File:Tutorials-Cadence-Schematic_TestInv_AddInstanceGND.gif]]
  
Left Click <strong>Hide</strong> and place the <em>vdd</em> and <em>gnd</em> symbols on the schematic<strong>.</strong> Place the <em>vdd</em> above the vdc symbol and <em>gnd</em> bellow the vdc symbol.
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Left Click '''Hide''' and place the ''vdd'' and ''gnd'' symbols on the schematic. Place the ''vdd'' above the vdc symbol and ''gnd'' bellow the vdc symbol.
  
Next, we want to add capacitor to the output pin in order  to  simulate a load (other circuits) that our inverter has to charge or  discharge.  Left click <strong>Editing:Add-&gt;Component</strong>. From the <strong>NCSU_Analog_Parts</strong> library  choose a cell named <strong>cap</strong> and specify its value to be <strong>1 pF</strong>. The Add Instance window should look like the one bellow:
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Next, we want to add capacitor to the output pin in order  to  simulate a load (other circuits) that our inverter has to charge or  discharge.  Left click '''Editing:Add &rarr; Component'''. From the '''NCSU_Analog_Parts''' library  choose a cell named '''cap''' and specify its value to be '''1 pF'''. The Add Instance window should look like the one below:
  
<img src="images/cadence_img/schematic_TestInv_AddInstanceCAP.gif" alt="add_cap" width="386" height="522">
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: [[File:Tutorials-Cadence-Schematic_TestInv_AddInstanceCAP.gif]]
  
Next we will add an output pin in the schematic.  Left  click <strong>Editing:Add-&gt;Pin</strong>. Name the pin <strong>out</strong> and  specify it  as an output pin. Place the pin next to the output of the  inverter.
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Next we will add an output pin in the schematic.  Left  click '''Editing:Add &rarr; Pin'''. Name the pin '''out''' and  specify it  as an output pin. Place the pin next to the output of the  inverter.
  
Connect all the elements as shown in the figure  bellow.  To connect different elements use <strong>Editing:Add-&gt;Wire. </strong>The final schematic should like the one bellow:
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Connect all the elements as shown in the figure  below.  To connect different elements use '''Editing:Add &rarr; Wire'''. The final schematic should like the one below:
  
<img src="images/cadence_img/sch_test_inv2.gif" alt="sch2" width="906" height="726">
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: [[File:Tutorials-Cadence-Sch_test_inv2.gif]]
  
 
Save the schematic and you are ready to simulate the  inverter.
 
Save the schematic and you are ready to simulate the  inverter.
  
In the  schematic of inv_test, left click <strong>Editing:Launch -&gt; ADE L</strong>. The spectre  window should appear.
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In the  schematic of inv_test, left click '''Editing:Launch &rarr; ADE L'''. The spectre  window should appear.
  
<img src="images/cadence_img/Spectre_DC1.gif" alt="spectre1" width="698" height="442">
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: [[File:Tutorials-Cadence-Spectre_DC1.gif]]
  
We want to specify the type of analysis we want to  perform.  We are going to select a DC analysis. Left click <strong>Analog Artist:Analyses-&gt;Choose?</strong> Click on the <strong>dc</strong> button for Analysis. Click <strong>Component  Parameter </strong>button for sweep variable. In the <strong>Sweep Range,</strong> fill <strong>0  and  5V </strong>for the start and stop. Left click on the <strong>Select Component</strong>.  Now go back to the schematic and select the voltage source you want to  sweep. Click on the vdc that is connected to the input of the inverter.  This will pop-up a small window, which requests the Parameter Name.  Click on <strong>dc </strong>to sweep the voltage.  Go back to your Analysis Choose window, which should look like the one  below, and click on OK.
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We want to specify the type of analysis we want to  perform.  We are going to select a DC analysis. Left click '''Analog Artist:Analyses &rarr; Choose?''' Click on the '''dc''' button for Analysis. Click '''Component  Parameter '''button for sweep variable. In the '''Sweep Range,''' fill '''0  and  5V '''for the start and stop. Left click on the '''Select Component'''.  Now go back to the schematic and select the voltage source you want to  sweep. Click on the vdc that is connected to the input of the inverter.  This will pop-up a small window, which requests the Parameter Name.  Click on '''dc '''to sweep the voltage.  Go back to your Analysis Choose window, which should look like the one  below, and click on OK.
  
<img src="images/cadence_img/Spectre_DC2.gif" alt="spectre2" width="416" height="666">
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: [[File:Tutorials-Cadence-Spectre_DC2.gif]]
  
Second, we want to select which output voltages to  be  plotted. Left click on <strong>Analog Artist:</strong> <strong>Outputs-&gt;To be  Plotted-&gt;Select  on Schematic.</strong> Click on the wire between your vdc source and the <em>in</em> pin of your inverter. Then click on the wire between the <em>out</em> pin  of the inverter and the <em>out</em> pin. Both wires should change color  indicating that these voltages will be plotted.
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Second, we want to select which output voltages to  be  plotted. Left click on '''Analog Artist: Outputs &rarr; To be  Plotted &rarr; Select  on Schematic'''. Click on the wire between your vdc source and the ''in'' pin of your inverter. Then click on the wire between the ''out'' pin  of the inverter and the ''out'' pin. Both wires should change color  indicating that these voltages will be plotted.
  
 
Note: If you want to select a current to be plotted,  then  click on the square of a symbol where the current is flowing through.  There  will be a circle around the square node indicating that a current is  selected.
 
Note: If you want to select a current to be plotted,  then  click on the square of a symbol where the current is flowing through.  There  will be a circle around the square node indicating that a current is  selected.
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Your Analog Environment window should appear similar  to:
 
Your Analog Environment window should appear similar  to:
  
<img src="images/cadence_img/Spectre_DC3.gif" alt="spectre3" width="698" height="442">
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: [[File:Tutorials-Cadence-Spectre_DC3.gif]]
  
 
Note: in order to make your simulation more readable, it is often  advisable to name special nets with uniquely identifiable names, so  that when the simulation results are presented, they are more easily  understood.
 
Note: in order to make your simulation more readable, it is often  advisable to name special nets with uniquely identifiable names, so  that when the simulation results are presented, they are more easily  understood.
  
You are ready to run the simulation. Left Click <strong>Simulation-&gt;Run</strong> or click on the green traffic light  icon in the Analog Environment window. The  result window, as the one below will appear shortly. Explore the pull  down menus in this window in order to customize your results. For  instance,  left click <strong>Axes-&gt;Strip</strong> in order to separate the different  curves.
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You are ready to run the simulation. Left Click '''Simulation &rarr; Run''' or click on the green traffic light  icon in the Analog Environment window. The  result window, as the one below will appear shortly. Explore the pull  down menus in this window in order to customize your results. For  instance,  left click '''Axes &rarr; Strip''' in order to separate the different  curves.
  
<img src="images/cadence_img/Spectre_DC4.gif" alt="spectre4" width="896" height="696">
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: [[File:Tutorials-Cadence-Spectre_DC4.gif]]
  
To plot the results left click <strong>Waveform Window:  Window-&gt;hardcopy</strong>.  Select the option to Send Plot Only to File and also don't forget to  disable  the header option in order not to waste paper. You might also disable  Mail  Log To to prevent it from mailing you about the status of printing.
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To plot the results left click '''Waveform Window:  Window &rarr; hardcopy'''.  Select the option to Send Plot Only to File and also don't forget to  disable  the header option in order not to waste paper. You might also disable  Mail  Log To to prevent it from mailing you about the status of printing.
  
Now exit the Cadence Spice. Left click on <strong>Analog  Environment:Session-&gt;Quit</strong>.  Remember NOT to save the current state. If you choose to save the  current  state, several hundreds of megabytes will be used in order to save your  last simulation.
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Now exit the Cadence Spice. Left click on '''Analog  Environment:Session &rarr; Quit'''.  Remember NOT to save the current state. If you choose to save the  current  state, several hundreds of megabytes will be used in order to save your  last simulation.
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<noinclude>
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[[Tutorials:Cadence:CreatingSymbolInverter|Prev]] : [[Tutorials:Cadence:SchematicSimulationTransient|Next]] : [[Tutorials:Cadence:Main|Up]]
  
  
 
----
 
----
 
{{Template:CadenceDisclaimer}}
 
{{Template:CadenceDisclaimer}}
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</noinclude>

Latest revision as of 18:52, 10 November 2010

Schematic Simulation: Creating a Test File for Simulating an Inverter

Now that we have built an inverter, we need to simulate it to show that our design is valid. First we need to create a new cell in our CSE463library for testing the inverter. In the Library Manager, highlight the test library and left click on Library Manager:File → New → Cell View.

In the Cell Name type inv_test and in the View Name type schematic. Left click on OK.

Tutorials-Cadence-Schematic TestInv.gif

A new schematic editing tool will appear. You are going to instance the inverter that was previously created and connect its input pin to voltage source. The output pin will be connected to a capacitor.

Left click Editing:Add->Instance. Click on the Library pull down menu and select the CSE463 library. Select the inv cell. The Component Browser window should look like the one bellow.

Tutorials-Cadence-Schematic TestInv ComponentBrowser.gif

Place the inverter in the middle of the editing window. Note: you can press F3 key while you have selected the symbol you want to place and the Add Instance window will appear. In this window, you can edit some of the properties of the symbol if applicable.

Now we want to add voltage DC sources. Left Click Editing: Add → Instance. In NCSU_Analog_Parts library; you will find vdc sources. Place them in the test circuit. Left Click Editing:Add → Instance. In NCSU_Analog_Parts library, under Voltage_Sources category, you will find vdc source. Place them in the test circuit. The Component Browser should look like the one below:

Tutorials-Cadence-Schematic TestInv ComponentBrowserVDC.gif

Select Vdc and Add Instance window will appear. In the DC Voltage field enter 5V. This window should appear as such:

Tutorials-Cadence-Schematic TestInv AddInstanceVDC.gif

Place the symbol to the left of the inverter.

Now we want to add global ground and power lines. Left Click Editing: Add → Instance. In NCSU_Analog_Parts library, under Supply_Nets category, you will find vdd and gnd sources. Place them in the test circuit. The Component Browser should look like the one below.

Tutorials-Cadence-Schematic TestInv ComponentBrowserGND.gif

Once you select the NCSU_Analog_Parts selection and select Supply_Nets, you will find gnd and vdd symbols. The Add Instance windows for vdd and gnd should look like the ones below:

Tutorials-Cadence-Schematic TestInv AddInstanceVDD.gif
Tutorials-Cadence-Schematic TestInv AddInstanceGND.gif

Left Click Hide and place the vdd and gnd symbols on the schematic. Place the vdd above the vdc symbol and gnd bellow the vdc symbol.

Next, we want to add capacitor to the output pin in order to simulate a load (other circuits) that our inverter has to charge or discharge. Left click Editing:Add → Component. From the NCSU_Analog_Parts library choose a cell named cap and specify its value to be 1 pF. The Add Instance window should look like the one below:

Tutorials-Cadence-Schematic TestInv AddInstanceCAP.gif

Next we will add an output pin in the schematic. Left click Editing:Add → Pin. Name the pin out and specify it as an output pin. Place the pin next to the output of the inverter.

Connect all the elements as shown in the figure below. To connect different elements use Editing:Add → Wire. The final schematic should like the one below:

Tutorials-Cadence-Sch test inv2.gif

Save the schematic and you are ready to simulate the inverter.

In the schematic of inv_test, left click Editing:Launch → ADE L. The spectre window should appear.

Tutorials-Cadence-Spectre DC1.gif

We want to specify the type of analysis we want to perform. We are going to select a DC analysis. Left click Analog Artist:Analyses → Choose? Click on the dc button for Analysis. Click Component Parameter button for sweep variable. In the Sweep Range, fill 0 and 5V for the start and stop. Left click on the Select Component. Now go back to the schematic and select the voltage source you want to sweep. Click on the vdc that is connected to the input of the inverter. This will pop-up a small window, which requests the Parameter Name. Click on dc to sweep the voltage. Go back to your Analysis Choose window, which should look like the one below, and click on OK.

Tutorials-Cadence-Spectre DC2.gif

Second, we want to select which output voltages to be plotted. Left click on Analog Artist: Outputs → To be Plotted → Select on Schematic. Click on the wire between your vdc source and the in pin of your inverter. Then click on the wire between the out pin of the inverter and the out pin. Both wires should change color indicating that these voltages will be plotted.

Note: If you want to select a current to be plotted, then click on the square of a symbol where the current is flowing through. There will be a circle around the square node indicating that a current is selected.

Your Analog Environment window should appear similar to:

Tutorials-Cadence-Spectre DC3.gif

Note: in order to make your simulation more readable, it is often advisable to name special nets with uniquely identifiable names, so that when the simulation results are presented, they are more easily understood.

You are ready to run the simulation. Left Click Simulation → Run or click on the green traffic light icon in the Analog Environment window. The result window, as the one below will appear shortly. Explore the pull down menus in this window in order to customize your results. For instance, left click Axes → Strip in order to separate the different curves.

Tutorials-Cadence-Spectre DC4.gif

To plot the results left click Waveform Window: Window → hardcopy. Select the option to Send Plot Only to File and also don't forget to disable the header option in order not to waste paper. You might also disable Mail Log To to prevent it from mailing you about the status of printing.

Now exit the Cadence Spice. Left click on Analog Environment:Session → Quit. Remember NOT to save the current state. If you choose to save the current state, several hundreds of megabytes will be used in order to save your last simulation.


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