Patent ID: 7990741

Claim:
A charge pump comprising: a voltage booster circuit having a first input terminal to receive a regulation voltage and a second input terminal to receive an input voltage, the voltage booster circuit generating an output voltage having a polarity that is different from the input voltage, the output voltage adjusted by the regulation voltage and provided to an output terminal; and a voltage regulator circuit coupled between the first input terminal and the output terminal of the voltage booster circuit, the voltage regulator circuit shifting the output voltage to a level shifted voltage and generating the regulation voltage responsive to the level shifted voltage; wherein the voltage regulator circuit comprises: a level shift circuit that receives the output voltage from the voltage booster circuit and generates the level shifted voltage; and a differential amplifier having an output terminal on which the regulated voltage is generated, the differential amplifier having a first input terminal coupled to a reference voltage and a second input terminal coupled to receive the level shifted voltage from the level shift circuit; and wherein the level shift circuit comprises: a capacitor having first and second terminals, the first terminal of the capacitor being coupled to the output terminal of the voltage booster circuit; a first switch coupled between the second terminal of the capacitor and a fixed voltage, the first switch being closed during a first phase of each of a plurality of cycles; and a second switch coupled between the second terminal of the capacitor and the second input terminal of the differential amplifier, the second switch being closed during a second phase of each of the plurality of cycles.