US Patent 7123077 Four-phase charge pump circuit with reduced body effect

A charge pump circuit has an input stage, an output stage and multiple boosting stages coupled between the input stage and the output stage. The boosting stages are driven by four phase clock signals. Each boosting stage has two branch charge pumps, wherein each branch charge pump at least has a main pass transistor, a pre-charge transistor, two substrate transistors and capacitors. The substrate transistors and the main pass transistor are operated in association with the four phase clock signals to keep a potential of the body of the main pass transistors at a low level thus mitigating the body effect.