Patent ID: 7368978
Filing Date: 2008-05-06
Classification: H02M

Abstract:
1. A charge pump comprising: a voltage output; a pump capacitor having first and second terminals; a first pump switching device connected in series between a first voltage and the first terminal of the pump capacitor; a second pump switching device connected in series between the second terminal of the pump capacitor and the voltage output; a charge switching device connected in series between a second voltage less than the first voltage and the first terminal of the pump capacitor; a charging transistor connected in series between the first voltage and the second terminal of the pump capacitor, the charging transistor regulating the first voltage to substantially reduce noise from the first voltage when charging the pump capacitor and subsequently at the voltage output, the charging transistor comprising a gate input to which a modulated voltage is applied and a bulk input to which a first regulated voltage is applied; and a regulator including a bandgap voltage generator supplying the first regulated voltage and varying the modulated voltage between the first regulated voltage and the first regulated voltage plus a nominal voltage, the nominal voltage enabling the modulated voltage to swing to either side of the first voltage.