Perform time domain noise analysis

How to perform time domain noise analysis. A time domain noise analysis is performed in transient mode simulation. This allows for simulations where the signals at all nodes of the system comes from the contribution of source signal and the noise.

1. Drag and drop the SIMCTRLR simulation controller block from the palette window in Simulation controls section to the schematic window.

   
   
   

2. Double-click on the SIMCTRLR block to open the Parameters window. By default, the Simulation name is "sim0" and it is editable. Here, we name the simulation "sim4_LNA_B-HF_with_time_domain_noise". 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.

   
   

   

   
   

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 signal that we will use in this simulation.

   
   

   

   
   

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.

     
     

     

     
     

5. In the Noise tab, choose the Time domain noise analysis and set the equations to define the noise bandwidth and the resolution frequency:
   • Ambient temperature (°C): this parameter will be used in the calculation of passive circuit noise.
   • Bandwidth (Hz): 1/t_step
   • Resolution frequency (Hz): 1/( (nb_sample-1)*t_step )

     
     

     

     
     

6. Now we will set up the schematic to simulate a LNA-B-HF model or a LNA-B-SP model. Drag and drop the LNA block from the palette window in Non linear section to the schematic window. Double-click on the LNA 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". Select the parameter Add noise for this block to be taken into account in noise analysis.

   
   

   

   
   

7. We will set up a simple pulsed signal. Drag and drop the PULSE-VS pulse generator block from the palette window in Source section to the schematic window. Double-click on the PULSE-VS block to open the Parameters window and set the parameters as shown in the following screenshot. Also, click on Noise tab and select the parameter Add noise for this block to be taken into account in noise analysis Connect the PULSE-VS block output [+] with the input [in] of the LNA block.

   
   

   

   
   
   

   

   
   

8. 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 1.28 GHz. Connect the DC-VS block output + with the input fc of the LNA block.

   
   

   

   
   

9. 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 LNA block. Double-click on the RES block to open the Parameters window and set the resistance to 50 Ohms. Connect the LNA block output [out] with the input [+] of the RES block.

   
   

   

   
   

10. To measure the waveform and the spectrum at the input and output of the model, drag and drop the Waveform block and 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:
    • Edit the Probe name to "input".
    • Choose dBm (Voltage wave) for Result Display parameter.

    Click on OK button to validate and close the parameters window. Connect the Spectrum input [1] with the LNA input block [in].
    Proceed in the same way with the other three blocks as in the following figure.
    

    

    
    
11. 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 "sim4_LNA_B_HF_with_time_domain_noise". In Workspace window, the Log shows console information. Click on Output graphs tab to access the measurements provided by the probes. Click on Waveform Probes in Figures section to display the output waveform. You can observe the presence of noise in the low state of the pulse.

    
    

    

    
    

13. We will run another simulation without noise analysis and compare the results. Double-click on the SIMCTRLR block to open the Parameters window and change the name of the simulation to "sim4_LNA_B-HF". Click on Noise tab and select the parameter No noise analysis. Close the Parameters window and run the simulation by clicking on Simulate>Run simulation or on the shortcut . After closing the console window, the results appears in the application tree in the folder named after the simulation "sim4_LNA_B_HF". Click on Output graphs tab to access the measurements provided by the probes. Click on Waveform Probes in Figures section to display the output waveform. You can observe the pulse waveform without the presence of noise.