US 6,522,114 B1Granted

Noise reduction architecture for low dropout voltage regulators

AssigneeKoninklijke Philips Electronics N.V.

InventorsAnton Bakker, Qing He

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Abstract

The present invention relates to a low dropout voltage regulator comprising a noise reduction architecture. The low dropout voltage regulator according to the invention comprises a comparison stage for comparing a reference voltage signal with a feedback signal and for providing a first output voltage signal in dependence thereupon. The feedback signal is obtained from a node interposed between a first resistor and a second resistor of a voltage divider. The voltage divider is interposed between an input port for receiving an input voltage signal and ground and is connected to an output terminal of the comparison stage. The first output voltage signal is then low pass filtered prior provision to a gain stage. The gain stage provides gain to the first output voltage signal prior provision to an output port. The noise reduction architecture of the low dropout voltage regulator according to the invention is highly advantageous by providing high efficiency while high frequency noise is substantially reduced.

Claims17

Dependent claims

A low dropout voltage regulator comprising:

an input port for receiving an input voltage signal;
an output port for providing a regulated output voltage signal;
a bandgap reference interposed between the input port and ground for providing a reference voltage signal;
a voltage divider comprising a first and a second resistor interposed between the input port and ground;
an error amplifier having a first input terminal coupled to the band gap reference, an output terminal coupled to a first node interposed between the voltage divider and the input port and a second input terminal coupled to a second node interposed between the first and the second resistor of the voltage divider, the error amplifier for comparing a bandgap reference signal received at the first input terminal with a feedback signal received at the second input terminal and for providing a first output voltage signal in dependence thereupon;
a X1 buffer having a first input terminal coupled to the output terminal of the error amplifier, a second input terminal coupled to the output port and an output terminal coupled to a gate terminal of a pass transistor, the pass transistor having a source terminal connected to the input port and a drain terminal connected to the output port, the X1 buffer for providing gain to the first output voltage signal in order to drive a load connected to the output port;
and,
a low pass filter interposed between the first node and the X1 buffer for filtering the first output voltage signal.

5 more elements

Dependencies are inferred from the claim text.