System and method for digital feedback circuit and analog feedback circuit

A method comprising:

• controlling an output voltage of a low-dropout (LDO) regulator using a digital control loop comprising:
• digitizing the output voltage of the LDO regulator, and
• activating at least one pass transistor based on the digitized output voltage using a drive circuit;
• and
• controlling the output voltage of the LDO regulator using a nested analog control loop comprising:
• amplifying the output voltage of the LDO regulator according to a transfer function having a non-zero direct current (DC) gain, and
• applying the amplified output voltage to an over voltage node of the drive circuit, wherein the digital control loop has a smaller bandwidth than the nested analog control loop.

A voltage regulator comprising:

• an analog-to-digital converter having an input coupled to an output node of the voltage regulator;
• a digital filter coupled to an output of the analog-to-digital converter;
• a drive circuit coupled to an output of the digital filter;
• a plurality of pass transistors having control nodes coupled to corresponding outputs of the drive circuit, and output nodes coupled to the output node of the voltage regulator;
• and a continuous-time analog feedback circuit comprising an amplifier having an input coupled to the output node of the voltage regulator, and an output coupled to an over voltage node of the drive circuit, wherein the analog feedback circuit has a non-zero direct current (DC) gain,
• wherein a bandwidth of a first control loop comprising the digital filter is less than a bandwidth of a second control loop comprising the analog feedback circuit.