Selective body bias for charge pump transfer switches

摘要

Techniques are presented for improving the efficiencies of multi-stage charge pumps by reducing the amount of voltage lost across the inter-stage transfer switches of the pump through use a selective body bias. The voltage level from both branches of one stage is each supplied though a corresponding diode to the bulk connection of the transfer switch after the subsequent stage in both branches. This arrangement results in each stage providing a largely uniform amount of gain, without the usual increase of voltage drop with increasing numbers of stages.

主权项

1. A charge pump, comprising:
first and second branches connected in parallel between a supply node and an output node, wherein each of the branches includes a plurality of stages connected in series, the first of which is connected to the supply node though a respective initial switch, each stage having:
a stage capacitor;a stage node connected to the corresponding stage capacitor; anda transfer switch, through which the corresponding stage node is connected to the stage node of the subsequent stage in the series, except for the final stage of the series, whose stage node is connected through the corresponding transfer switch to the output node, wherein, when the charge pump is enabled, even and odd stages in the series of the first branch are respectively connected to receive first and second clock non-overlapping clock signals and even and odd stages in the series of the second branch are respectively connected to receive the second and first clock signals; and first and second diodes through which the stage node of a first one of the stages in the series of both of the first and second branches are respectively connected to provide, for both of the first and second branches, a body bias of the transfer switches of the stage subsequent to the first one of the stages.