Creating the first simulation

Authors: Jihoon Jeong, Shaver Deyerle, Justin Cartwright, Dr. Dong S. Ha

1. To start simulation, choose Tools->Analog Environment from the top menu, Analog Design Environment (ADE) will appear. Click on Setup-> Simulator/Directory/Host... , choose spectre as the "Simulator" and click OK. Then select Variable->Copy from cellview, you will see all the variables defined in schematic show up in "Design Variables section". Double click each variable and set its value as you wish. (Fig. 11)

Note: L and C value are 47.74n and 1.91p respectively to meet the given condition. You may say L value is too big to be implemented. Yes! We will have to apply other matching networks (π network or T network) to satisfy our given condition and feasibility. I'll leave that problem to you. :)

2. Next select Analysis->Choose.. or click on the Choose Analyses.. button on the right toolbar. Choosing Analyses window will appear. This is where you have options to run many different types of analysis from DC to noise simulations. Select the option sp, and more options will appear in the box below. Under the Ports section, click on the select button. Now look at your schematic window, click on port 'P1' and 'P2' in order. (You may see green circles appear at the nodes of the ports.) You should see "/P1 /P2" in the Ports filed of the Choosing Analyses window. Please escape by hitting 'ESC' when you have done adding ports.

3. Make sure "Sweep Variable" is Frequency, then set "Sweep Range" from 1 to 10 GHz. (Note: Type 10G for 10 GHz). Select Logarithmic as a "Sweep Type" and give number of "Points Per Decade" (Note: 101 points will be enough). Leave all other settings as is, and click OK. (Fig. 11)

Figure 11. Set values for variables and Choose Analysis

4. Click the "green" traffic signal on the right toolbar, Netlist and Run... Output log window will pop up and report simulation progress. In addition, the window will provide debugging information for warnings, errors in the event that errors are present. (Fig. 12)

Note: Welcome Spectre window will appear if it's the first attempt for you to run spectre simulation. You could check "Do not show the text again" at the bottom of the window unless you want to close Welcome Spectre window whenever you try to run simulation.

Figure 12. Output log window

5. In order to plot results, select Results->Direct Plot->Main Form... Direct Plot Form window will appear. Check the SP option under "Function", and select Rectangular "Plot Type" and Magnitude "Modifier". Click S21(Gain) or S12(Reverse Gain) button. The output function will be saved if you activate "Add to Outputs" at the bottom of the window. A Waveform window titled S-Parameter Response shows the selected s-parameter along the desired frequency range.(Fig. 13) Play with other options. You should be able to see that the maximum gain of the 2-Port Network occurs at 500 MHz as we appropriately add L and C values.

Note: We have plotted S21(Gain) and S12(Reverse Gain) of our system. You are strongly encouraged to check S11 and S22 as well to confirm that our matching network has the minimum reflection.

Figure 13. Direct Plot Form window and Waveforms plotted

6. Go back to the Direct Plot Form window and select the "Plot Type" to Z-Smith (Smith Chart), then click on any s parameter. You will be able to explore Smith Chart which will give a gain and phase information along with the desired frequency range. (Fig. 14)

Figure 14. Z-parameters in Smith Chart

If you have any question regarding on this tutorial, please feel free to contact me, Jihoon Jeong. (jihoon@vt.edu)

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