An ultra-low output voltage regulator

The transistor 2N797 used as a diode is a germanium tube, while the 2N2222 is a silicon tube. Its reference voltage is generated by the bandgap voltage difference between the two tubes, and its value is about 0.5V. LM111 is not an ordinary operational amplifier, but a voltage comparator specially designed for very low input current. When powered by a 5V power supply, its minimum output voltage can be adjusted to 0V. The circuit with the structure shown in the figure can adjust the minimum output voltage to nearly 500mV. The temperature coefficient of the entire voltage stabilization circuit is also very low.