using IC 5.10.40
I am working on VCO using MOS Varactor(B D S connected and inversion mode)but i am facing the problems listed here..
1 Finding the capacitance and quality factor. I also want to plot these with tuning voltage.
2 Which analysis i should use for that,
3 If we see the DC operating points, there are various capacitances. Which one to be used to calculate the total capacitance.
4 Calcilating capacitance between two nodes.
Not really enough to go on, but my guess is that you should do an sp (s-parameter) analysis. Can't really answer the other questions because you've given so little information.
I have simulated a 5 Gh VCO. I STARTED it by applying a SINGLE CURRENT PULSE at one of the output node.But the frequency of oscillations is varing a lot with CURRENT PULSE AMPLITUDE and CURRENT PULSE WIDTH.
for 1mA current and 5p pulse width it is 4.5Gh and 5mA current it is 5.9Gh.
Why this is so because as far as i know the oscillation frequency should not depend on VCO STARTING METHOD.
Can u please suggest another method of kicking the oscillator which will be reliable.