Lab Work I

8/20/2019 Lab Work I

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HRK Lab 1 – MOSFET Characteristics

KEEE 4469 Analog VLSI Circuit Design SEM-1 2013/2014 1/8

LAB 1: MOSFET Characteristics

Objectives:1. To study the semiconductor device characteristic of a MOSFET.2. To define the behavior of the MOSFET in terms of its terminal voltages and currents.3. To carry out the parametric analysis for MOSFET.

Procedure: 1. Double clicks at icon VMware Workstation, clicks Power on This Virtual Machine. Next, type in the

Username and password and press enter.

2. Red Hat Linux 4 will appear. Then right click and chose Open Terminal. In the terminal, type cdsilterraC13_Apr2011 command and press enter. Next, type virtuoso command and press enter.

3. After Virtuoso window appear, click Tools > Library Manager. The Library Manager:WorkArea wilappear.

4. To create your working directory in Library Manager, click File > New > Library, then insert youlibrary name for example “Lab” in the new pop up New Library window. Then click OK.

5. Then Technology File for New Library will pop up. Choose Attach to an existing techfile button andclick OK.

6. Select silterraC13 and click OK at Attach Design Library to Technology File window.

7. In the Library Manager:WorkArea window, the new library “Lab” has been created.

8. To create the schematic workspace, highlight your library name “Lab” , then go to File > New > CelView. Then insert your Cell Name “Lab1” in the new Create New File window and click OK.

9. The Virtuoso Schematic Editor will apprear for you to create your schematic.

10. Construst the schematic given in Figure 1.

W 20µm

L 130 nm

=

GSV=DC DSV V

1M

Figure 1 : Schematic of NMOS transistor

11. To choose the component, click Add > Instance. Then, click the Browse button to find the componentthat you want as shown in Figure 2. To change the parameters of the instance, select the instance (byclicking on it with the mouse) and then use “properties” icon or press “q”.


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Figure 2 : Instantiation of the single stage transistor

12. Complete plugging in the parameter of the circuit as given in Figure 1. Click at Check and Save buttonto check and to automatically save your design. Make sure you look at the CIW window and there areno errors or warnings, if there are any, you have to go back and fix them.

13. Click Launch > ADE L to simulate the circuit. In the Analog Design Environment window, click Setup >Simulator/Directory/Host , choose spectre and click OK as shown in Figure 3.

Figure 3 : Selected Simulator (Spectre)

14. In the Virtuoso Analog Design Environment window, click Setup > Model Libraries, delete all themodel files and choose the correct Model File and Section as shown in Figure 4.


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Figure 4 : Selected model library

15. Then click OK. Your Analog Design Environment window will appear for you to select the inpuVariables. Click Variable > Edit then the Editing Design variables window will appear. Insert the inputvariables in the Name column and its value in the Value (Expr) column, and then click OK, as shownFigure 5.

16. For the output, click Outputs > To Be Plotted > Select On Schematic. Here you need to choose theoutput from the schematic (in this case, select the negative terminal of VDS supply). Press Esc afteselecting the output. Be sure at the Outputs > Save All > click “all” button to save all your simulationoutput results.

Figure 5 : Analog design environment

/home/eda/silterraC13_smartPDK_4_1_21Apr2011/models/SPECTRE/bsim4c13_hprf_rev1_2.scs


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17. Then choose the analysis type by click Analyses > Choose > dc and click on Save DC OperatingPoint. Then click at Design Variable box, insert the Variable Name and Sweep Range as shown inFigure 6 and click OK.

Figure 6 : Simulation of single stage

18. Finally, to run simulation, click Simulation > Netlist & Run. The graph that shows I/V characteristicsfor NMOS will appear. Your graphs should be similar as in Figure 7 and Figure 8. It shows graph for

DSI vs GSV (when DSV = 1.2 V) and DSI vs DSV (when GSV = 600 mV).

Figure 7 : DSI vs GSV when DSV = 1.2 V


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Figure 8 : DSI vs DSV graph when GSV = 600 mV

(Note: If there is any change of schematic, click at Check and Save button. Recreate netlist needs tobe done in the Analog Design Environment, click Simulation > Netlist > recreate first then Simulation> Netlist & Run)

19. To determine various values of GSV , click Tools > Parametric Analysis. Then Parametric Analysis wil

pop up. Then click Setup > Pick Name for Variable > Sweep 1. Choose the variable GSV form the

Parametric Analysis Pick Sweep 1, and then click OK.

20. Then insert the Range type and Step Control as show in Figure 9. Then click Analysis > Start toobtained the results as shown in Figure 9.

Figure 9 : Parametric analysis of single stage amplifier

21. The graph obtained after simulation should be as shown in Figure 10. Record the reading in Table 1.


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(a)

(b)

Figure 10 : NMOS characteristics, (a) DSI vs DSV and (b) DSI vs GSV

Table 1: Result of DSI vs DSV

( )GSV V 0.5 0.6 0.7

( )DSI µA

( )DSV V 0.9 0.9 0.9

(Note: In the Analog Design Environment, save the dc analysis process that was evaluated by clickingSession > Save State > dc_NMOS_analysis.)

22. What is the value of DSV when DSI = 150 µA and GSV = 0.6 V?

23. Applying the same steps to obtain the DSI vs DSV , we can obtain the DSI vs GSV graph as shown in

Figure 10(b). The graph shows that the smaller the SBV is the higher DSI will flow through the NMOS.


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24. To plot the mg graphs ( mg vs TNGSV - V ), in Analog Design Environment, click Tools > Result

Browser. Result Browser window will pop up, click dcOpInfo-info > NM0 > main choose “gm” anduse right hand button to select Calculator. Calculator window will pop up containing the gm info thawas selected in Result Browser.

25. Go back to the Analog Design Environment, double click at the VDD/MINUS in the Outputs area topop up the Setting Output window. Click on New Expression button, follow by Get Expressionbutton. In the Expression column there is the detail about the mg that was selected before. Type in

any name in Name (opt.) column such as mg . Click OK.

26. Go back to the Result Browser window, select “vgs” then use right hand button to select CalculatorWithout do other things, repeat the same procedure to select “vth” following by clicking minus (-) buttonin the Calculator. Now, in the calculator display both “vgs” and “vth” information will be appearedRepeat the same step as in procedure 25 and type in any name in Name (opt.) column such as vgs-vth. Click OK.

27. Simulate the data that was in the Analog Design Environment. Ensure to sweep your GSV from 0 to

1 in Parametric Analysis and produce the graph as shown in Figure 11. (To change the axis, doubleclick on the axis and the Axis Attributes window will pop up for editing). Explain the graph.

Figure 11 : mg vs TNGSV - V graph when W/L constant

28. Using the same procedure, plot mg vs DSI (when W/L constant) and mg vs TNGSV - V (when DSI

constant by adding a 2 mA Current Source to the Drain of schematic). Your graph will be as shown inFigure 12 and Figure 13.


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Figure 12 : mg vs DSI when W/L constant

Figure 13 : mg vs TNGSV - V when DSI constant

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