hhq414
Member level 1
nyquist condition oscillation phase gain
As we know,when the phase shift at the open loop pll bandwith is bigger than
-180+PM,where PM stands for phase margin and is ususlly >45 degree,we say the pll is stable.I am confused that in a second order pll the phase shift in the frequency near dc is almost -180 degree, but we usually don't care about that. How can it be stable when the frequency is near dc?
As we know,when the phase shift at the open loop pll bandwith is bigger than
-180+PM,where PM stands for phase margin and is ususlly >45 degree,we say the pll is stable.I am confused that in a second order pll the phase shift in the frequency near dc is almost -180 degree, but we usually don't care about that. How can it be stable when the frequency is near dc?