"internal teamsteap error" in oscillator design

[Coust]

Hello there again. I have been working with this oscillator few days ago and it's working fine with this configuration:


The problem appears when i'm trying to bias the bottom mosfet with a DC 1.8V pulse. I need the oscillator to turn on and turn off to get a OOK modulation, this is the reason that i'm trying to switch it with a pulse source.

When I do this with the DC pulse source I get the "timesteap is too small" error. I've tried to increase the rise/fall of the source because I know that sometimes it fix the problem, but it doesn't work this time. I know that the problem is caused by that pulse source because the oscillator works fine with a DC source of 1.8V so probably it's something related to an voltage/intensity that grows too much when I switch the source.

Any advice/tips?

Ty very much, I don't know what I had done without your advices!

 

[BigBoss]

You can not modulate the oscillator while you simulate it.The simulator will confuse the circuits' node equations.
Try first without modulation since your oscillator work smoothly with HB and then apply " Envelope Simulation" with your modulating signal.

 

[Coust]

You can not modulate the oscillator while you simulate it.The simulator will confuse the circuits' node equations.
Try first without modulation since your oscillator work smoothly with HB and then apply " Envelope Simulation" with your modulating signal.

So, do you mean that I should use a HB simulation with a "Envelope Simulation" instead of the transient one? Can that "Env. Simul." realise that I'm working with two diferent frequency?

 

[vfone]

I just did recently a very similar simulation (and built) of a pulse controlled oscillator and everything works fine. Even simple freeware spice simulators would work for this simulation.
The only difference was that I used a FET oscillator, modulated in the source by a pulsed BJT.
You have to be sure that in your simulation the starting time of the initial oscillator is fast enough when is supplied by Vcc.

 

[Coust]

Before I get the error I can take those pictures:


Looking at those pictures I would say that the problem is at the simulation itself not in the oscillator devices but I can be wrong. Current grows until some MA, so it doesn't make sense.
Lowering the mosfet's bias dosen't make the difference. I can low it until 0.1V and the picture is still the same. When I try to bias at 1.5V and a 2kohm resistance instead of 1.8V and 6kohm it seems that the oscillator works better but I don't understand why the current is so large when I have a 0V bias. It suppose to be switched off.

Pictures:



Does anyone know why is it happening?

Ty very much for your answers.

 

[BigBoss]

A transient simulation is possible but HB will not converge while it's looking for the oscillator frequency.
An envelope simulation will show you both center frequency and side-bands due to modulation frequency.
Or..
Try a give a settling time to the oscillator.

 

[Coust]

A transient simulation is possible but HB will not converge while it's looking for the oscillator frequency.
An envelope simulation will show you both center frequency and side-bands due to modulation frequency.
Or..
Try a give a settling time to the oscillator.

Sorry but I don't understand what do you mean by "settling time". How I do that?

Ty very much for your answers.