Double charge pump circuit with triple charge sharing clock scheme

A double charge pump circuit with triple charge sharing clock scheme is described. The proposed charge sharing clock generator is able to recover nearly two-thirds of the charge from the parasitics charging, in which way the dynamic power loss in the pumping process is reduced to almost one-third. To preserve the overlapping period of the four-phase clock used for threshold cancellation technique, two complementary sets of clocks are generated from the proposed clock generator, and each set feeds a certain branch of the double charge pump to achieve a between-branch charge sharing. Under 0.18µm technology with a bottom plate parasitic ratio of 0.2, the simulation results of a proposed 5-stage charge pump circuit show an overall efficiency increase with a peak value of 62.8% comparing to 46.8% of a conventional one, and the output ripple voltage is reduced by nearly a half.