Low dropout regulator and ring oscillator

The low dropout linear regulator is provided with a comparison circuit, a buffer circuit, a power switch tube, a feedback network and an overshoot voltage stabilizing circuit, the buffer circuit comprises a first transistor, a second transistor and a third transistor which are sequentially connected in series between a power supply voltage and a reference ground, the fourth transistor is connected between the grid electrode of the power switch tube and the reference ground and is used for realizing a negative feedback mechanism of the buffer circuit, so that the output impedance of the low-dropout linear regulator can be reduced under the condition that the low-dropout linear regulator has a relatively small area, and the stability of the circuit can be conveniently improved; the ring oscillator comprising the low dropout linear regulator and a PTAT voltage generation circuit can realize process, power supply voltage and temperature compensation of the ring oscillator, and greatly improves the stability of th