Simultaneous low quiescent current and high performance LDO using single input stage and multiple output stages

1. A low dropout (LDO) voltage regulator, comprising:

a first pass transistor;

a second pass transistor, wherein a source of the first pass transistor is coupled to a source of the second pass transistor and the sources of the first and second pass transistors are configured to receive an input voltage (Vin);

an output node to provide an output voltage;

a first resistor coupled between the output node and a feedback node;

a second resistor coupled between a ground and the feedback node;

an error amplifying module having a first output, a second output, a first input, and a second input, the first output coupled to a gate of the first pass transistor, and the second output coupled to a gate of the second pass transistor, wherein the error amplifying module further includes

a first output stage coupled to the first output, the first output stage configured to drive the gate of the first pass transistor during a high performance (HP) mode,

a second output stage coupled to the second output, the second output stage configured to drive the gate of the second pass transistor during the HP mode and during a low power (LP) mode, and

an input stage having a first input, a second input, and an output, wherein the first input is configured to receive a reference voltage, the second input is coupled to the feedback node to receive a feedback voltage (Vfb), the first output is coupled to the first output stage of the error amplifying module, and the output is coupled to the first and the second output stages of the error amplifying module,

wherein the second output stage of the error amplifying module comprises:

a p-type field effect transistor (pFET) having a source, a drain, and a gate, wherein the source is configured to receive the Vin, the gate and the drain are coupled to the gate of the second pass transistor; and

an n-type field effect transistor (nFET) having a source, a drain, and a gate, wherein the source is coupled to the ground, the drain is coupled to the drain of the pFET, and the gate is coupled to the output of the input stage;

wherein the first output stage of the error amplifying module comprises:

a first pFET having a source, a gate, and a drain, wherein the source is configured to receive the Vin;

a second pFET having a source, a gate, and a drain, wherein the source is configured to receive the Vin, the gate and the drain are coupled to the gate of the first pFET;

a first nFET having a source, a gate, and a drain, wherein the source is coupled to the ground, the drain is coupled to the drain of the first pFET, and the gate is coupled to the output of the input stage; and

a third pFET having a source, a gate, and a drain, wherein the drain is coupled to the ground, the source is coupled to the drain of the second pFET, and the gate is coupled to the drain of the first nFET;

a first switch coupled between the source of the first nFET and the ground;

a second switch coupled between the gate of the third pFET and the Vin; and

a third switch coupled between the gate of the second pFET and the Vin; and

a fourth switch coupled between a gate of the first pass transistor and the Vin,

wherein the first switch is configured to be off and the second, third, and fourth switches are configured to be turned on in the LP mode.

2. The LDO voltage regulator of claim 1 , wherein the first switch is configured to be on and the second, third, and fourth switches are configured to be turned off in the HP mode.

3. The LDO voltage regulator of claim 1 , wherein the first pass transistor is larger than the second pass transistor.

4. A system on chip (SoC), comprising the LDO voltage regulator of claim 1 , and a core circuit, wherein the core circuit is coupled to the output node of the LDO voltage regulator, and the core circuit is configured to be powered by the output voltage from the LDO voltage regulator.

5. The SoC of claim 4 , wherein the Vin is provided by a battery.