Voltage regulator with a minimal input voltage requirement

A voltage regulator for providing a constant voltage at an output terminal, wherein said voltage regulator comprises:

• an input stage including an operational amplifier having a positive amplifier input, a negative amplifier input, and an amplifier output having an amplifier output signal proportional to a difference between a first signal on said positive amplifier input and a second signal on said negative amplifier input;
• an output stage including a p-channel power MOSFET device, driven by said amplifier output signal, providing a voltage output at said output terminal, wherein a positive input voltage is applied to said output stage at a source of said power MOSFET device, wherein said output terminal is connected to a source of said power MOSFET device, and wherein a gate of said MOSFET device is driven by said amplifier output;
• a reference voltage applying a positive voltage to said negative amplifier input;
• a first feedback loop extending through said input stage and said output stage, said first feedback loop including a first feedback portion extending from an output of said output stage to said positive amplifier input;
• and
• a second feedback loop extending through said input stage, said second feedback loop including a second feedback loop portion extending from an output of said input stage to said negative amplifier input.

A voltage regulator for providing a constant voltage at an output terminal, wherein said voltage regulator comprises:

• an input stage including an operational amplifier having a positive amplifier input, a negative amplifier input, and an amplifier output having an amplifier output signal proportional to a difference between a first signal on said positive amplifier input and a second signal on said negative amplifier input;
• an output stage including an n-channel power MOSFET device, driven by said amplifier output signal, providing a voltage output at said output terminal, wherein a negative input voltage is applied to said output stage at a drain of said power MOSFET device, wherein said output terminal is connected to a source of said power MOSFET device, and wherein a gate of said MOSFET device is driven by said amplifier output;
• a reference voltage applying a negative voltage to said negative amplifier input;
• a first feedback loop extending through said input stage and said output stage, said first feedback loop including a first feedback portion extending from an output of said output stage to said positive amplifier input;
• and
• a second feedback loop extending through said input stage, said second feedback loop including a second feedback loop portion extending from an output of said input stage to said negative amplifier input.

A voltage regulator comprising:

• a voltage reference;
• an input amplifier having a positive amplifier input, a negative amplifier input to which said voltage reference is applied, and an amplifier output providing an amplifier output signal having a voltage level proportional to a voltage difference between said positive amplifier input and said negative amplifier input;
• an output stage, including a power transistor, driven by said amplifier output signal;
• an output terminal connected to an output of said power transistor in said output stage
• a first feedback loop applying a first feedback signal proportional to a voltage of said output terminal to said positive amplifier input;
• and
• a second feedback loop applying a second feedback signal to said negative amplifier input, wherein said second feedback signal is derived by passing said amplifier output signal through an impedance and wherein said second feedback signal stabilizes operation of said voltage regulator.

A voltage regulator comprising:

• an input amplifier having a positive amplifier input, a negative amplifier input to which said voltage reference is applied, and an amplifier output providing an amplifier output signal having a voltage level proportional to a difference between said positive amplifier input and said negative amplifier input;
• a voltage reference applying a positive voltage to said negative amplifier input;
• an output stage driven by said amplifier output signal, wherein said output stage includes a p-channel power MOSFET device having a gate driven by said amplifier output signal, a source to which a positive input voltage is applied, and a drain to which said output terminal is connected;
• an output terminal connected to said output stage;
• a first feedback loop applying a first feedback signal proportional to a voltage of said output terminal to said positive amplifier input;
• a second feedback loop applying a second feedback signal to said negative amplifier input, wherein said second feedback signal is derived by passing said amplifier output signal through an impedance and wherein said second feedback signal stabilizes operation of said voltage regulator.

A voltage regulator comprising:

• an input amplifier having a positive amplifier input, a negative amplifier input to which said voltage reference is applied, and an amplifier output providing an amplifier output signal having a voltage level proportional to a difference between said positive amplifier input and said negative amplifier input;
• a voltage reference applying a negative voltage to said negative amplifier input;
• an output stage driven by said amplifier output signal, wherein said output stage includes an n-channel power MOSFET device having a gate driven by said amplifier output signal, a source to which a negative input voltage is applied, and a source to which said output terminal is connected;
• an output terminal connected to said output stage;
• a first feedback loop applying a first feedback signal proportional to a voltage of said output terminal to said positive amplifier input;
• a second feedback loop applying a second feedback signal to said negative amplifier input, wherein said second feedback signal is derived by passing said amplifier output signal through an impedance and wherein said second feedback signal stabilizes operation of said voltage regulator.