AC and Transient Analog Simulation with Accusim


1. Create a schematic of a simple RC network with Design Architect
 
1.1 If you are not in the directory where you originally did the first tutorial, go back there now:
>> cd egre224/tutorials
1.2 Start Design Architect to create the schematic of the circuit for this tutorial:
>> da &
1.3 Use your knowledge of DA to create a new component called circuit2 and construct a schematic for it using generic analog parts that looks like the one below:

1.4 Check and save the sheet and exit DA.

1.5 Use DVE to create a simulation viewpoint for Accusim as you did in the first tutorial.
 

2. Perform an AC simulation and analysis of the RC network with Accusim
 
2.1 Start the Accusim simulator on the circuit2 design;
>> accusim circuit2 &
2.2 Select the Vin node in the schematic window and click the Add Force button in the palette. In the Force dialog box, set the Mode to Frequency and the Force Type to AC. Set the Magnitude item to 5 and click OK in the Force dialog box.

2.3 Click the Setup Analysis button in the palette. In the Setup Analysis dialog box that comes up, set the Analysis item to AC. Set the Start Freq item to 1 and the Stop Freq item to 100Meg (100 MHz).  Leave the Sweep Type item set to Decade and click OK.

2.4 Use the Setup->Keeps->Keeps... menu item to bring up the Add Keeps dialog box and click OK.

2.4 Select the Vin and Vout nodes in the schematic window and click the Trace button in the palette. Click the Run button in the palette. The result should be a Chart window like the one below:

2.5 Use the Setup-Results-Define Waveform menu item to bring up the Define Waveforms dialog box. Use the method you learned in the previous tutorial to define a waveform called gain that has an expression of vm(vout)/vm(vin) (voltage magnitude of vout divided by voltage magnitude of vin) and a waveform called phase_shift that has an expression of vp(vout)-vp(vin)  (voltage phase of vout minus voltage phase of vin).

2.6 Use the Setup->Keeps->Keeps... menu item to bring up the Add Keeps dialog box again and click OK.

2.7 Click on the Run button in the palette area to run the simulation again.

2.8 Use the Results->Chart->Chart/Trace Defined Waveforms menu item to bring up the Chart Defined Waveforms dialog box. Click the Trace button and select the gain waveform. Click OK in the dialog box. Use the same method to trace the phase_shift waveform. The result should be a chart window like the one below.

Note that you can make the chart window larger and move the legend or make it smaller to see all of the waveforms.
 

3. Perform a transient simulation of the RC network with a square wave input
 
Now that you have plotted the circuit's frequency response (gain vs. frequency), you will examine how the circuit behaves with a square wave on its input.

3.1 Close the existing Chart window.

3.2 Make the schematic window active and unselect everything (hit the F2 key). Select the "force bubble" on the Vin node and hit the delete key to remove the force. Select the Vin node and hit the Add Force button in the palette. You may have to hit the DC Mode button in the palette first to make the Add Force button visible.

When the Add Force dialog box comes up, set the Mode item to Time and set the Force Type to Pulse. Set the Initial Value to 0 and the Pulsed Value to 5. Set the Pulse Width to 1U and the Pulse Period to 2U (milliseconds) and click OK.

3.3 Click on the Setup Analysis button in the palette and set the Analysis item to Transient. Set the Time Step item to 0.001U and the Stop Time to 10U and click OK.

3.4 In the schematic window, select the Vin and Vout nodes and click on the Trace button in the palette.

3.5 Click on the Run button in the palette to run the simulation. The result should be a trace window like the one below:

3.6 Exit the Accusim simulator.