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Problem with the VCO

Martin Dickhoff
Prodigy 60 points


2768.VCO_ASLK.TSC

Hello,

I have a problem with the VCO. I build it with the Analog System Lab Kit Pro and use a signal with an Offset-Voltage and it works. The same shematic don't work in TINA with a Signal with an Offset-Voltage. I don't know where the problem is. I have to use a signal with an Offset Voltage for a project so I hope you can help me because i don't what i could do. I try so much but it don't work.

Best regards

Martin

  • 0
    TI__Mastermind 40295 points

    Martin,

    A transient sim of your circuit resulted in a convergence error.

    The OP2 gain circuit was configured with positive feedback, making that part of the circuit unstable.
    It was reconfigured with negative feedback, and an E-source with a gain of -1 was inserted after that stage to keep the overall OP1/OP2 gain path negative.

    With this change, a transient sim seems to run okay. As a check, the signals all seem to be centered around mid-supply (0V), as opposed to being near the power supplies.

    Hope this helps. The modified circuit is attcahed to this thread.

    Regards,
    John

    2768.VCO_ASLK[2].TSC
  • 0 in reply to John Miller - Sensing
    Prodigy 60 points

    Hey John,

    thank you for your answer. I tried to work with the circuit you send me but the problem is that it don't work like a VCO now. I don't know why. I tried to generate an FM-Signal with it but it dosen't work now. in the circuit I send to you i get a FM-Signal but there was just the Problem that i can't use an input signal with an Offset-Voltage.

    I don't understand why I get no FM-Signal now.

    Hope you can help me.

    Regards

    Martin