In this type of a voltage regulator error amplifier and PMOS are supply from the same voltage. But even if error amp is supply from the large voltage than PMOS. The error amp will still be able to turn ON PMOS.
Initially when Vout = 0V and Vfb = 0V the error amp see large different between Vbg and Vfb (Vdiff = 0V - 1V = -1V).
The error amplifier will now amplify this negative Vdiff voltage to produce a negative-going output voltage.
And this is why the output of the error amp will go toward negative direction ( towards 0V). And this voltage for sure will turn ON the PMOS.
Initially when Vout = 0V and Vfb = 0V the error amp see large different between Vbg and Vfb (Vdiff = 0V - 1V = -1V).
The error amplifier will now amplify this negative Vdiff voltage to produce a negative-going output voltage.
And this is why the output of the error amp will go toward negative direction ( towards 0V). And this voltage for sure will turn ON the PMOS.
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