Apparatus for a two phase bootstrap charge pump

Abstract

An integrated circuit charge pump circuit including a plurality of stages, each stage including a first N type field effect switching transistor device having source and drain terminals connected in series with the source and drain terminals of all other stages, a second N type field effect control transistor device having drain and source terminals connecting the drain terminal and the gate terminal of the first switching transistor device, and a storage capacitor joined to the source terminal of the first device; a source of voltage to be pumped is connected to the drain terminal of the first device of the first stage. A first series of clock pulses is applied to the gate terminals of the first switching transistor devices in every other stage of the charge pump and to the gate terminals of the second control transistor devices in stages between; and a second series of clock pulses which do not overlap the first series of clock pulses is applied to the gate terminals of the first switching transistor devices in alternate stages of the charge pump and to the gate terminals of the second control transistor devices in stages between the alternate stages. These pulses cause the switching transistor to switch on and off in alternate stages in a manner that the gate terminal goes higher than the drain terminal so that charge is transferred without threshold drop between stages and high current as well as high voltage is pumped to the output terminal.