pspice mixed signal simulation problem

[kleinesmurf69]

Hello,

I am having trouble simulating a multivibrator circuit followed by some digital parts. I get a lot of simulation messages and the voltages are way to high, the vibrator does not properly oscillate any more... Does anyone have an example mixed signal project in orcad pspice? Can you share?

Thank you.

Best regards.

 

[papyaki]

Hi,

I think you need to specify an initial condition value for the capacitor you use in the multivibrator. This parameter is labeled "IC". You can find it in the capacitor's parameters. Try setting this parameter to 0 or to a value equal to the power supply's one.

 

[kleinesmurf69]

Have already taken care of this IC. The multivibrator oscillates properly when there isn't any gate attached. Setting the IC=0V gives better results, but they're still wrong. After the gates the oscillation is lost, probably because of the wrong voltage levels in the multivibrator. The voltage levels of the oscillator should be symmetrical around the zero axis and have an amplitude equal to the power supply. This asymmetry is also present without the gates, but it is smaller. The circuit has been build and worked properly. The purpose of the current simulations is to be able to simulate/design these kind of circuits prior to building them in the future.

Best regards.