Some questions about VCO during desinging !!!

[zhaozenghui]

Some questions about VCO find help!

1.picture of lift :this wave do not symmetry,can ?

2.At voltage of 0 v,there is wave ,can??

thanks!!

 

[khouly]

yeah it can be done , this is the DC component in the node , to elemiate it use AC coupling cap

khouly

 

[Ti_W]

try the ideal DCBLOCK in ads，you can use a proper capacitor instead of it

 

[BigBoss]

Strange..
Second harmonic is higher than main carrier..
I guess there are some assymmetric structures in your oscillator.See Fig-1..
Even tough there is DC component, the waveform proofs me about assymmetry in your circuit.
Also, start-up delay time seems to be very long for an oscillator that operates at those frequencies..

I think your design has some serious problems.If you post your circuit, I can help you more..

 

[trayant]

ur swing is too low..
if u put a DC value with this .. it will show u a DC as well.. mean.. no oscillation.. typical voltage swing will at least 0.5~ 0.8, some design can get full swing as well