Perform Transient simulation

How to perform transient simulation. The transient simulation in VISION allows to obtain the time domain response of a non-linear circuit excited by a modulated complex signal.

To begin this task, you will need:The basic steps to perform a transient simulation are:
  1. Drag and drop the SIMCTRLR simulation controller block from the palette window in Simulation controls section to the schematic window.
    Figure: Simulation controller block


  2. Double-click on the SIMCTRLR block to open the Parameters window. By default, the Simulation name is "sim0" and it is editable. In the Simulation mode tab, choose the Simulation mode by selecting Transient simulation. We will use two variables to fill the Final integration time, in seconds, and the number of time points. We will describe in the next step how to set up these variables. Choose the Analyse type by selecting Nominal analysis. In the Solver tab, choose the Solver Type by selecting Algebraic solver I.
    Figure: Simulation mode


  3. Drag and drop the EQN equation block from the palette window in Simulation section to the schematic window. Double-click on the EQN block to open the Parameters window. We create two parameters:
    • nb_sample: to define the number of time samples.
    • t_step: to define the time step of the simulation.
    These parameters are related to the modulated signal that we will use in this simulation.
    Figure: Equation bloc


  4. Double-click on the SIMCTRLR block to open the Parameters window et write the equations in the following parameters:
    • Final integration time: (nb_sample-1)*t_step.
    • Number of time points: nb_sample.
      Figure: Final integration time and number of time points


  5. Now we will set up the schematic to simulate a HPA-U-HF model. Drag and drop the HPA block from the palette window in Non linear section to the schematic window. Double-click on the HPA block to open the Parameters window and fill in the Model parameter file field with the absolute or relative path of your extracted model in device modeler with the extension ".head".
    Figure: HPA block


  6. Drag and drop the AWG-VS arbitrary waveform generator block from the palette window in Source section to the schematic window. Double-click on the AWG-VS block to open the Parameters window, fill in the Model parameter file field with the absolute or relative path of your data file containing the signal record ('p1f7wave.dat' in the data_example folder), choose dBm as Signal unit, set the Signal average power and set 50 ohms as value of the Internal impedance. Connect the CW-VS block output [+] with the input [in] of the HPA block.
    Figure: AWG-VS source block


  7. Drag and drop the DC-VS block from the palette window in Source section to the schematic window. We will use this block to indicate the carrier frequency of the CW signal to the HPA block. Double-click on the DC-VS block to open the Parameters window, change the signal type to "real signal" and set the carrier frequency in DC value field. For this example, the carrier frequency is 3 GHz. Connect the DC-VS block output + with the input fc of the HPA block.
    Figure: Set the carrier frequency


  8. Drag and drop the RES block from the palette window in Linear lumped section to the schematic window. We will use this block to present a 50 Ohms load at the output of the HPA block. Double-click on the RES block to open the Parameters window and set the resistance to 50 Ohms. Connect the HPA block output [out] with the input [+] of the RES block.
    Figure: Present 50 Ohms load at the output of the HPA model


  9. We will now place probes and scopes to measure spectrum, waveform and adjacent channel power ratio (ACPR). In a transient simulation, we use the W-meter block. Drag and drop two W-meter blocks from the palette window in Probe section to the schematic window:
    • Place the first W-meter block between the AWG-VS source block and the HPA block.
    • Connect the AWG-VS block output [+] with the W-meter block input [1].
    • Connect the W-meter block output [2] with the HPA block input [in].
    • Place the second W-meter between the HPA block and the RES block.
    • Connect the HPA block output [out] with the W-meter block input [1].
    • Connect the W-meter block output [2] with the RES block input [+].
    The W-meter block allows to measure incident and reflected power waves, respectively A and B. Double-click on the W-meter block to open the Parameters window and choose Incident & Reflected power wave (A-B) as Probe type.
    Figure: Place W-meter block on the schematic


  10. To measure the input and output spectrum, drag and drop the Spectrum block from the palette window in Scope section to the schematic window. Double-click on the Spectrum block to open the Parameters window:
    • Change the number of channels to 2.
    • Edit the Probe name to "Spectrum"
    • Choose dBm (A power wave) for Result Display parameter.
    • Edit the Channel names to "input_spectrum ; output_spectrum".
    Click on OK button to validate and close the parameters window. Connect the Spectrum input [input_spectrum] with the first W-meter output block [a]. Connect the Spectrum input [output_spectrum] with the second W-meter output block [a].
    Figure: Spectrum block


  11. Double-click on the SIMCTRLR block to open the Parameters window and edit a name to the simulation. Here we change the name for "sim1_HPA_U_HF. The model can now be simulated. In the menu bar of the workspace window, click on Simulate>Run simulation or on the shortcut . The output console is displayed:

    The console window contains the simulation time, the simulation mode, the repertory of the results, and also any warnings and errors encountered during the simulation.
  12. When closing the console window, simulation results appear in the application tree in the folder named after the simulation "sim1_HPA_U_HF". In Workspace window, the Log shows console information. Click on Output graphs tab to access the measurements provided by the probes. Click on Spectrum Probes in Figures section to display the input and output spectrum.
    Figure: Output graphs


    It is found that the spectrum are quite noisy. You can improve the display of the spectrum with the Envelope trace parameter of the Spectrum block. Here, we choose 1 as filter order and we run the simulation. Using the same simulation name, this overwrites the existing result folder.
    Figure: Output graphs with envelope trace option


  13. We will place 2 probes to measure the low and up ACPR. We use the ACPR block. Drag and drop the ACPR block from the palette window in Probe section to the schematic window and connect the ACPR input block [in] with the W-meter output block [a]. To specify the bandwidths in the ACPR blocks, we will define several variables in the EQN block: the symbol rate, the roll-off and the occupied bandwidth.
    Figure: Equations for bandwidth calculation


    Figure: ACPR block


  14. We will place a probe to measure the power consumption Pdc of the model. We use the waveform block. Drag and drop the waveform block from the palette window in Scope section to the schematic window and double-click on the waveform block to open the Parameters window. We will choose Real signal as Signal Type, edit the name of the probe as "Pdc" and choose Real and imaginary as Result Display parameter. Then, connect the HPA block output Pdc with the waveform block input 1 and run the simulation.
    Figure: Pdc measurement


  15. When closing the console window, click on the simulation "sim1_HPA_U_HF" in the Applications window and click on Output graphs tab to access to the results of power consumption.
    Figure: Output results of Performance monitor block