Patent ID: 8436597
Filing Date: 2013-05-07
Classification: G05F

Abstract:
1. A low drop-out DC voltage regulator comprising: an output pass element for controlling an output voltage of power supplied from a power supply through the output pass element to a load; a source of a reference voltage; and a feedback loop for providing to said output pass element a control signal tending to correct error in the output voltage, said feedback loop including a differential module including a differential amplifier responsive to relative values of said output voltage and said reference voltage and an intermediate module driven by said differential module for providing said control signal, the regulator presenting a cut-off frequency at which its regulation gain becomes less than one, said differential amplifier comprising a common base emitter follower circuit including a first transistor and a second transistor, an emitter of the first transistor coupled to said output voltage and an emitter of the second transistor coupled to said reference voltage; wherein said differential module presents the widest bandwidth of the modules of the regulator and said differential module presents a frequency pole that is higher than said cut-off frequency, and said feedback loop includes a further amplifier element comprising a capacitive element such as to increase gain of said differential module at low frequencies, the low drop-out DC voltage regulator being stable as measured by the phase margin whatever the values of the load resistance and capacitance.