Low-dropout voltage regulator with improved stability for all capacitive loads

摘要

The present invention provides an LDO that is stable for all capacitive loads. Because the LDO is stable for all capacitive loads, the ESR (equivalent series resistance) inherent in any capacitive load can no longer affect the equivalent value of the combination of the ESR and the capacitive load. Thus, the invention also effectively removes the ESR restrictions on the loads. According to the present invention, a low dropout voltage regulator is provided. The regulator comprises a switching element (e.g., a transistor) having first terminal for receiving an input signal, a second terminal for providing an output signal and a control terminal; a control circuit, operably coupled to the switching element, that is configured to control the switching element; and a compensation circuit having a first segment connected between the first and control terminals of the switching element and a second segment connected between the control and second terminals of the switching element. The first segment of the compensation circuit includes a first resistor and the second segment of the compensation circuit includes a RC circuit. In one embodiment of the invention, the RC circuit includes a second resistor and a capacitor connected to each other in series. In another embodiment of the invention, the RC circuit includes a distributed RC network having a plurality of resistors and capacitors.