hanikapa
Member level 4

I have designd a usual LC oscillator that is controlled by applying voltage to NMOS varactors. When I put a resistance between control voltage and varactors, I see there are periodic ripples on the varactor node. The importance of this point is that I use the VCO in PLL and this ripples in PLL creates more noise. Does anybody knows if these ripples on the control voltage of LC VCO is natural? What should I do to remove them?
Thanks
Thanks