Patent ID: 8305066

Claim:
A low dropout regulator, converting an input voltage to an output voltage to drive a load, comprising: a power transistor, having a power terminal, a control terminal and an output terminal, wherein the power terminal receives the input voltage; a current-voltage converting circuit, coupled to the output terminal of the power transistor to convert a received current to the output voltage; a current variation sensing circuit, having an input terminal coupled to the power transistor, and having a first output terminal and a second output terminal, and generating a first voltage variation and a second voltage variation at the first and the second output terminals, respectively, wherein the first and second voltage variations are generated according to a current variation of the power transistor and are of different transition speeds; and a compensating circuit, controlling the control terminal of the power transistor according to a first voltage difference between a feedback of the output voltage and a reference voltage and a second voltage difference between the second and the first output terminals of the current variation sensing circuit, wherein the current variation sensing circuit further comprises: a first current mirroring transistor and a second current mirroring transistor, each coupled to the power transistor to mirror current of the power transistor; a first diode and a first capacitor coupled in parallel between the first current mirroring transistor and a fixed voltage terminal, wherein the first diode, the first capacitor and the first current mirroring transistor are connected at the first output terminal of the current variation sensing circuit; and a second diode and a second capacitor coupled in parallel between the second current mirroring transistor and the fixed voltage terminal, wherein the second diode, the second capacitor and the second current mirroring transistor are connected at the second output terminal of the current variation sensing circuit.