Preparing the Circuit for Simulation

We will have to first load the project from the main menu. The steps followed for this simulation exercise is:

1. From the File menu of Project Explorer, select Open Project. Select Amplif.EPB file name from the file list in Open dialog box and then click the OK button.

2. Right click on the task CIR2. Right click on the task CIRCUIT in Project Explorer to unfold a list of functions and select Mixed Mode Simulator. We will observe that preprocessing of the circuit takes place. Preprocessing involves analyzing the Schematic and checking for the Simulation Function. It will list the data that it extracts along with statistics of the circuit. This includes the number of digital and analog nets, number of primitives, number of digital inputs, and outputs, number of A/D input / outputs. This is presented as a dialog box.

Simulation Function – assignment conventionalues

Analog components - Negative values

Digital components - Positive values

Unsimulated components - 0

3. Click CLOSE button to close this dialog box. The simulator is now ready for making further an3. Click CLOSE button to close this dialog box. The simulator is now ready for making further analysis on the circuit.

Note: While the Simulator is open, if any changes are made to the circuit in Schematic Editor, always ensure that the circuit is preprocessed so that the changes are reflected in the Simulator.

The circuit used for analysis is a RC amplifier. In the simulation exercise, we will analyze the bias points, study the operating state of the amplifier and modify the bias conditions to correct the operating state if needed. We will use Bias Point, Transient Analysis, DC Sweep, AC Sweep, Monte Carlo and Sensitivity Analysis from the Analysis menu and display the results using Waveform Viewer.

4. First define the points at which the analog net voltage is to be analyzed. Right click and select the function tool Testpoint and then select the option tool Voltage TP. Place Voltage Testpoints display boxes at convenient locations at all the circuit’s net where the voltage is to be displayed after the analysis. Click on the wires to place Voltage testpoints.

5. Next, select the function tool Waveform Markers and then the option tool Voltage Waveform. Place Voltage Waveform Markers near the Testpoints or at points where the output waveform is to be analyzed. Click on the wires to place Voltage testpoints.

6. To analyze the capacitor current, right click and select the function tool Testpoint and then the option tool Current TP. Point to the right pin of the capacitor and place the Current Display Testpoint close to it.

7. Select the option tool Current Waveform from the function tool Waveform Marker and click on an entry of a component and place the Current Waveform Mark beside.

After placing the testpoints and the waveform markers, the circuit is ready for various Analysis. from the filThe amplifier circuit is purely an analog circuit. We will now exercise the other functions of the simulator in analyzing the Half Adder circuit.

1. From the File menu of the Project Explorer, select Open Project. Select Half_Adder.EPB file name from the file list in the Open dialog box and then click the OK button.

2. Open Mixed Mode Simulator, the circuit is preprocessed on start. .

3. According to the preprocessing data, the circuit has been recognized as having 1 analog and 4 digital nets. It is mandatory for Mixed-Mode Simulation to define the ground net SPL0, although it may not be used in the Schematic. The analog net SPL0 simulates digital parts ground.

4. The nets named A, B, SUM and CARRY are digital nets.

5. Click the CLOSE button to close this dialog box.

Note: While the Simulator is open, if any changes are made to the circuit in Schematic Editor, always ensure that the circuit is preprocessed so that the changes are reflected in the Simulator.

6. We will have to define the parameters of the various active components. Right click and select the function tool Set parameters/ models and then the option tool Set Parameter. Point to the AND Gate and click. The system displays the rise and fall time parameters defined for this family. These parameters are included in the primitive by default. If however the user wishes to change these, it can be done in this dialog. Close the dialog box.

7. Similarly set the parameters for the XOR Gate.

8. Next, set the input stimuli to the circuit. This can be done by selecting the Function tool Preset Logic State and then the Option tool Clock Generator.

9. Click on the wire where the input has to be applied, in the case of Half Adder it has to be the input wires A and B. Click on A, an input box appears. Enter the string (L20u,H20u), a label G! gets tagged to the cursor, place it next to the wire A. Similary click on B and enter the string (L10u,H10u).

This string (L20u,H20u) is a clock generator which will generate a clock signal with 20µs low and 20µs pulses. Since this string is enclosed within brackets, this will repeat the pattern given in the string till the Final Time specified in Simulation menu | Analysis.

10. After the analysis is carried out, the results are either displayed in the Waveform Viewer. Right click and select the function tool Waveform Marker and then the option tool Logic Waveforms. Now click on net A and place the waveform marker near the wire. Similarly click on the other nets, B, CARRY and SUM and place their respective waveform markers.

11. Select the Simulation menu | Analysis, the Setup Simulation Parameters window appears. Select the Transient Analysis checkbox in the right pane and then select Transient Analysis in the left pane. Enter the following values

Analog Sim. Step Time – 1µs

Sim. Time Limit – 40µs (you may assign any value greater than this value)

Display Waveform – Enable checkbox

Now press ACCEPT and then START. Waveform Viewer will be launched with the Simulation results.