Sine Wave Oscillator Simulation on Multisim 14.2

Updated Jun 7, 2023

Reported In

Software

  • Multisim

Operating System

  • Windows

Issue Details

I have designed a single transistor sine wave generator circuit in the Multisim 11.0 which gives correct simulation results, that is I see sine wave generated accordingly. The screenshot is below:
11th.png

The same circuit in the Multisim 14.1 doesn't show generation, instead, DC voltage is seen on the oscilloscope window. The screenshot is below:
14th.png

Is this a bug?

Solution

This issue is related to the Maximum time step (TMAX) parameter and it is not a bug. Simulation of rapidly changing processes such as periodic analog signal or pulse generation, oscillation requires appropriate time step value setting. Having a smaller value than required will lead to wrong simulation results.
The default TMAX values for Multisim 11.0 and Multisim 14.1 are 1e-09s and 1e-05s, respectively.
Set TMAX value to 1e-09 in the Analysis parameters of simulation settings on Multisim 14.1 (see screenshot below) and run the simulation.

2021-06-18_125443.png

This will lead to the right simulation results.
 

Additional Information

Before proceeding with simulation make sure to have all simulation parameters and settings set accordingly.
Take into account the following:
  • A small value for TMAX results in more accurate simulations (smoother curves). However, the simulations take longer to complete.
  • Conversely, a large value for TMAX results in very fast simulations. However, the simulation accuracy may degrade.
To determine the best value for TMAX chooses it based on the Nyquist sampling theorem.

Related Links

 Multisim Manual

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