Voltage regulator and bandgap voltage reference with novel start-up circuit and seamless voltage reference switch over for psr enhancement

A method for voltage regulation in a system using a voltage regulation loop that comprises:

• a voltage reference generation block comprising at least one bandgap voltage reference circuit, a selector, and a control block;
• a linear voltage regulator block that comprises a first linear voltage regulator and a second linear voltage regulator, wherein the first linear voltage regulator provides a first regulated power supply to the at least one bandgap voltage reference circuit in the voltage reference generation block, and the second linear voltage regulator (provides a second regulated power supply to a load;
• and a soft startup circuit connected between the voltage reference generation block and the linear voltage regulator block, the method comprising:
• providing a system power supply to the at least one bandgap voltage reference circuit in the voltage reference generation block to generate a voltage reference to the soft startup circuit, which then outputs a smooth voltage reference to the linear voltage regulator block to start up the first linear voltage regulator and the second linear voltage regulator;
• generating a first regulated voltage, using the first linear voltage regulator and the system power, wherein the first regulated voltage is used as a supply for the voltage reference generation block;
• and
• generating a second regulated voltage, using the second linear voltage regulator and the system power, wherein the second regulated voltage is used to power a load of the system.