I have been looking into making a voltage controlled oscillator using varicap diodes, however I have had hard time simulating the diodes in spice.

Would anyone here have an idea how this would be done?

Thanks in advance

  • \$\begingroup\$ Diode models have baseline capacitance and exponent used in the reverse-voltage effect on capacitance. \$\endgroup\$ – analogsystemsrf Sep 17 '17 at 2:32
  • \$\begingroup\$ Have you tried searching the net for (your) models to see if they work? \$\endgroup\$ – a concerned citizen Sep 17 '17 at 5:55

Maybe you can solve your problem by using variable capacitance models (intially found on the LTSpice Yahoo group I think ). spice_simulation_circuit

The equation governing the charge and voltage of a capacitor is \begin{equation} Q = CV \end{equation} In LTSpice, you cannot change the capacitance value. Rather you specify the charge of the capacitor. Hence, you specify your capacitor value as: \begin{equation} q = V{(\text{your capacitance node})} \cdot x \end{equation} where x is the voltage over the capacitor in question. This is covered in the LTSpice Help file under C. Capacitor


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