1. Start the cadence software msfb &
2. In the CIW do,
File->New->Library . A form titled "Create Library" will show up .
Fill the name & path for the library(e.g - HW7_lib) .
Click on Attach to existing tech library . In the adjoining cyclic field select AMI 0.6u C5N(3M,2P,high-res) .
Leave the default values for rest of the fields. Click on OK . The form disappears
& now you will be able to
see the library in the Library manager.
3. We will create
the schematic & Layout of an inverter. In the Library manager click on
the library created(e.g testlib).
Choose File->New->Cell View . You will see a form titled "Create New File". Fill
in the Cell name as "Inv" &
View Name as "schematic". Click OK to close the form.
4. Another window
titled "Virtuoso Schematic Editing: <Libname> Inv schematic"
shows up.
Choose Add->Instance a form titled Add Instance shows up. click
on the Browse . A
window titled "Component Browser" turns up(as shown). In this the library
filed should be set to "NCSU_Analog_Parts".
Click on P_Transistors . It will
show a listing of all the PMOS availabe in the library. Click on pmos4(pmos with substrate
connection).
The form enlarges . Fill in the required width & length in microns. When
you move the mouse over the schematic
window,
you will see a transistor attached to it. Click on the
schematic window to place the pmos.
5. To place the nmos Select
N_transistors from the Component Browser. choose nmos4 . In the "Add
instance" form fill the required
width & length . Place the nmos in the Schematic window.
6. Using the "Add wire " command make the required connections to form the inverter.
7. Add the input pin "A" &
the output pin "Z". Do a check & save . We will add the power
supplies & the input pulses required to
simulate the schematic.
8. In the schematic
window "Add instance" . Again the component browser appears . Click
on Supply_Nets . Choose vdd from the
listing & connect it to Source of the Pmos. Without closing the
"Add instance" form choose gnd from the "Component Browser"
window & connect it to the source of the nmos.
9. Now we have
to specify the value of vdd. Instantiate the "vdd" & "gnd " supply
nets again as shown in the e.g inverter given.
We have to connect a dc source of 5V between this vdd & gnd. On the "Components
browser" window click on Voltage_sources.
Choose vdc from the listing . The "Add Instance" form
enlarges , specify a value of 5V in the DC voltage field & leave the
rest of
the fields blank. Connect the vdc as shown in the inverter given.
10. We will connect
a pulse source to the input "A" . Just below vdc in the components
browser you will see vpulse which should be
selected . In the "Add instance form" fill in the required values for "Voltage1,
Voltage2, Delay time, Rise time, Fall time . Pulse
Width, Period". All the above fields exactly correspond to the
pulse statement of SPICE3.
11. Connect this source
to the input pin A as shown in the example schematic. Now we can simulate
this circuit
with SpectreS.
12. In the Schematic
Window do Tools->Analog Environment. A window titled "Affirma Analog Circuit Design Environment"
(which we will call SimW) pops up. In the design section of the window you
will see the design which is to be simulated.
13. In SimW do Setup->Simulator/Directory/Host . Choose spectreS as the simulator. Leave rest of the fields to the
default value.
The window should look like the one below . click OK to close the form .
14. We have to specify the type of analysis that should
be done. Click Analyses->Choose. Choose tran for transient analyses.
Specify the time upto which you want the transient analyses to run
in the Stop Time field. The form should look as shown.
Click OK to close the form.
15. We also need to set up the model path by selecting Setup-> Model Path... and add the following path: /eng/tools/cadence_3/local/models/spectre/nom/
16. The outputs to be plotted should be chosen from the
schematic. Do Outputs->To Be Plotted->Select
on Schematic. If you go to the schematic window , you will see
"Status: Selecting outputs to be plotted" at the
top of the window & "modify_plot" at the bottom . To select a node, click
on the corresponding wire connected to the output node. Check to See if
the node appears in the "Outputs" section of the SimW .
If it doesn't delete whatever unwanted node has appeared. First select the
unwanted node from the outputs section , then using Outputs->Delete menu from the SimW, remove
the node.
Repeat the procedure till you have selected all the output
nodes to be plotted.
17. Now it is time to run the simulation. Do Simulation->Run from the SimW. Spectre does the netlisting of the design & then does a transient analysis of the design. All the messages appear in the CIW as the simulation progresses. At the end of the simulation the SimW looks like :
If you see the following message :
spectre completes with 0 errors, 0 warnings, and 1 notice.
Spectre FINISHED.
elapsed time 108 S
...successful.
reading simulation data...
...successful.
in the CIW, then your simulation has completed successfully. You will see a waveform window opening, with all the output nodes you selected being plotted on the same axis. On the Waveform window choose Axes->To Strip , then all the outputs will be plotted as separate graphs. If your simulation was not completed successfully , try troubleshooting by looking at the CIW or contact the TA's during the Lab.
