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Envelope Simulation of a FM VCO.

Alli

Hi,

I'm having a VCO and trying to modulate the control voltage of the VCO and check the output spectrum.

The difference between the oscillator frequency and the modulation frequency is huge. Therefore, in order to make the simulations faster I tried to use the envelop simulation. As I understand and tested if the Fast env mode is off it would be really slow almost same as transient, to make the simulation faster I have to use the Fast env mode (level1 or level2), But it requires modulation source I/Q, though i don't have any I and Q channel. All I have it the control voltage of the VCO which is swept linearly between two values.

What I have to choose as the I/Q channel? (BTW, It requires both I and Q.)

If you have any hints to simulate FM VCO with envelop analysis please share it with me.

Thanks,

Ali

Parents

  • Andrew,

    Thanks for your response. Yes, I'm using HB mode. My settings are: (Sorry, I couldn't upload a picture of my setup)

    Envelop Following Analysis: Classic

    Engine: Harmonic Balance (I have nport (s-parameter) in my schematic so shooting mode doesn't work.)

    Stop time: 20u. (Is set equal to period of the signal which is modulation the control voltage of the VCO, I set it to 20u to at least capture one period.)

    Tones: Frequencies

    Oscillator option is checked marked and the related parameters are assigned.

    Fast envlp mode: Off

    In the user's guide envelop analysis of 2007, I read about "envelope ana for FM signal using speed up method ", but I couldn't find this option.

    If you have any other suggestion for the settings or another solution to make this simulation faster please let me know. 

    PS. My structure is a VCO with a periodic ramp voltage connected to the control voltage. 

    Thanks,

    Ali

Reply

  • Andrew,

    Thanks for your response. Yes, I'm using HB mode. My settings are: (Sorry, I couldn't upload a picture of my setup)

    Envelop Following Analysis: Classic

    Engine: Harmonic Balance (I have nport (s-parameter) in my schematic so shooting mode doesn't work.)

    Stop time: 20u. (Is set equal to period of the signal which is modulation the control voltage of the VCO, I set it to 20u to at least capture one period.)

    Tones: Frequencies

    Oscillator option is checked marked and the related parameters are assigned.

    Fast envlp mode: Off

    In the user's guide envelop analysis of 2007, I read about "envelope ana for FM signal using speed up method ", but I couldn't find this option.

    If you have any other suggestion for the settings or another solution to make this simulation faster please let me know. 

    PS. My structure is a VCO with a periodic ramp voltage connected to the control voltage. 

    Thanks,

    Ali

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