Soft-start low voltage CMOS LDO

The paper presents a soft-start low voltage CMOS LDO. A double-reference bandgap was developed to provide the soft-start feature. The first reference is quicker and drives the start-up circuit, while the second is slower and, after being divided, drives the LDO core. This circuit technique allows the reduction of the supply voltage and the control of the output voltage rise time through an external capacitor in order to reduce the inrush current at start-up. Also, there is no overshoot on the output voltage at start-up, even for large capacitive loads.