from my opinion,
1. ur amp have 2 pole 1 zero, and the zero is between there two pole
the bode plot is o.k.
2. Usually in opamp, the zero will not so ahead the second pole, in ur case ur zero is move before the second pole for more than 10 times.
3. from (1) this amp should be stable when the feedback is connect from Vout to "-".
4. u must be using "-" terminal as ur AC input, so in dc u will always get a inverse "180" phase shift.
I am not good at transfering netlist to schematic.
Anyway if you change the following lines
V1 V1 vcm ac 0.5 180
V2 V2 vcm ac 0.5
I think you can get the right phase plot.
It seems that your amp is a single output amp.
So why not simulate the open loop characteristics with the figure shown in the attachment? L0 and C0 can be set as large as you want,V2 can be used to set the CM voltage.
This opamp phase margin is -58, not + 58.
It's unstable.
At DC, the phase is 180, at unit-gain freq, the phase is about -58. That is , the phase shife is more than 180.
I guess you use two-stage opamp, and the RHP zero is not cancelled by the nulled resistor.
1. whenever you put the AC signal at the input, it must be at the input that use for negative feedback. Then you can get the phase start to roll off at 0 degree.
2. The best way according to me is to see where the phase response is starting from. Assuming that u have biased ur opamp in proper negative feedback:
a.) If the phase curve starts from 180 degrees, then PM should be measured w.r.t. the 0 degree axis i.e. the Phase value itself will give u the PM.
b.) If the phase curve starts from 0 degrees, then PM should be measured w.r.t. the -180 degree axis i.e. the Phase value + 180 degrees will give u the PM.