OP-AMP phase margin 및 unity gain frequency 구하기

** gain measure
.measure ac   'gain(db)'      max vdb(out0)
.measure ac   'gain(mag)'      max vm(out0)

** unity gain frequency
.measure ac funit trig at=1 targ vdb(net_name) val=0 fall=1

** phase margin
.measure ac phase_0dB find vp(net_name) when vdb(net_name)=0
.measure ac PhaseMargin = param('180+phase_0dB')