Low dropout voltage regulator circuit including gate offset servo circuit powered by charge pump

Abstract

A low drop out voltage regulator includes an error amplifier (,) having a first input coupled to a first reference voltage (V,), a second input receiving a feedback signal, and an output (,) producing an output signal (V,). An output transistor (,) has a gate, a drain coupled to an unregulated input voltage (V,), and a source coupled to produce a regulated output voltage (V,) on an output conductor (,). A feedback circuit (,) is coupled between the output conductor (,) and a reference voltage (GND) to produce the feedback signal. A capacitor (,) is coupled between the output (,) of the error amplifier and the gate (,) of the output transistor (,). A servo amplifier (,) has a first input coupled to a second reference voltage (VV,), a second input coupled to the output (,) of the error amplifier. A low current charge pump circuit (,B) supplies an output current into a supply voltage terminal of the servo amplifier. A variable reference voltage circuit (,) produces the second reference voltage (VV,) so as to increase the dynamic range of the voltage regulator. An output current sensing circuit (,) operates to produce a control signal (,) representative of the drain current of the output transistor (,), the variable reference voltage circuit (,) having an input coupled to receive the control signal (,).