a charge pump is disclosed for amplifying an input voltage received at an input end and outputting the amplified voltage at an output end as an output voltage . the charge pump includes a plurality of source / drain coupling transistors for serving as charging capacitors , and a plurality of cascode - connected transistors being symmetrically connected to between the input end and the output end . the charge pump further includes a plurality of diode - connected transistors to protect the source / drain coupling transistors against breakdown during the course of charge transfer and to speed up the charge transfer .