Patent ID: 7710091
Filing Date: 2010-05-04
Classification: G05F

Abstract:
1. A low dropout linear voltage regulator comprising: an input terminal receiving input DC voltage and an output terminal outputting a stabilized output voltage; a power transistor, wherein the source of said power transistor is coupled to said input terminal, and the drain of said power transistor is coupled to said output terminal; a first-stage amplifier, wherein the anti-phase input terminal of said first-stage amplifier receives a reference voltage signal input by a reference voltage generator, and the in-phase input terminal of said first-stage amplifier is coupled to a node, and a first Miller compensation capacitor is arranged in between the output terminal of said first-stage amplifier and the drain of said power transistor; a second-stage amplifier, wherein the input terminal of said second-stage amplifier is coupled to the output terminal of said first-stage amplifier, and a second Miller compensation capacitor and an active resistor cascaded to said second Miller compensation capacitor are arranged in between the output terminal of the second-stage amplifier and the drain of the power transistor; a feedback resistor network arranged in between the drain of said power transistor and the in-phase input terminal of said first-stage amplifier, wherein said feedback resistor network has two resistors, which form a voltage divider, and said node is formed in between said resistors; a capacitor-sharing circuit, wherein said capacitor-sharing circuit includes a shared capacitor, and said capacitor-sharing circuit detects the current of said power transistor and switches said shared capacitor to connect in parallel with said first Miller compensation capacitor or said second Miller compensation capacitor.