A low drop output regulator may be used for power management. The low drop out regulator may include an amplifier network having a transfer function may be used to provide a substantially constant voltage and variable current to a load. A zero compensation network may be used to add a zero to the transfer function that varies with the load current.

A low noise voltage regulator circuit with fast stable output voltage is disclosed. The low noise voltage regulator circuit contains a reference voltage generator, for generating a reference voltage; a switching circuit, which is electrically coupled to the output of reference voltage generator and has two states; and a stabilizing circuit. When the switching circuit is at a first state, the reference voltage is coupled to the stabilizing circuit without being filtered; when the switching circuit is at a second state, the reference voltage is filtered by a low pass filter before being coupled to the stabilizing circuit. A switching control signal is used to switch the switching circuit between the two states. The filtered reference voltage is used to generate a low noise regulated output voltage.

A compensated regulator includes a transconductance stage having a positive input for receiving a reference voltage, a negative input, and an output, an adjustable compensation block coupled between the output of the transconductance stage and ground, a feedback circuit having a first node coupled to the output of the compensated regulator, a second node coupled to the negative input of the transconductance stage, and a third node coupled to ground, and a driver stage having an input coupled to the output of the transconductance stage, a current output coupled to the output of the compensated regulator, and a sense output coupled to the adjustable compensation block.

A voltage regulator comprises a differential amplifier for comparing an output of a reference voltage circuit with an output of a voltage dividing circuit and outputting a first signal and a phase compensating circuit having a resistor and a capacitor connected in series. A MOS transistor is connected between a power supply and the phase compensating circuit and has a gate electrode connected to receive the output of the differential amplifier and a grounded source. A constant current circuit is connected between the MOS transistor and ground, and an output transistor having a gate electrode connected to receive a second signal output from a connection point between the MOS transistor and the phase compensating circuit is connected between the power supply and the voltage dividing circuit. A resistor side of the phase compensating circuit is connected to an output terminal of the differential amplifier and a capacitor side of the phase compensating circuit is connected to a drain electrode of the MOS transistor.

A voltage regulator having an output terminal adapted to being connected to a load, including an operational amplifier having its non-inverting input connected to a reference voltage, and its inverting input connected to the output terminal, an inverting amplifier having its input connected to the output of the operational amplifier, a capacitive impedance connected between the input and the output of the inverting amplifier, a power switch controlled by the output of the inverter amplifier, arranged to connect the output terminal to a first supply voltage, said capacitive impedance including a short-circuitable portion associated with active short-circuit means when the current flowing through the load is greater than a predetermined current.