Making CMOS Output Voltage, VDD and VSS Equal in Multisim

Updated Jan 25, 2018

Reported In

Software

  • Multisim Base

Issue Details

I am using the CMOS digital components in NI Multisim and I set the VDD voltage to 3.3V. When I run the simulation and then I measure the output, I am reading 5V. How do I make the output voltage the same as VDD voltage?

Solution

Multisim treats digital input and output as high or low behind the scenes, Multisim converts a high to the component default voltage level which in this case is 5V. By assuming a high is 5V, Multisim can simulate faster. 

If you want the CMOS components to use the VDD voltage:
  1.  From the main menu select Simulate»Mixed Mode Simulation settings
  2. Select Use Real pin model.

Additional Information

This setting will force Multisim to add a pin driver to every digital input and output to convert a high and low logic to VDD and VSS.
This setting will also cause the simulator to take longer than usual to finish depending on the circuit complexity.